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PLATE I • THE CIRCULATION 



SECOND BOOK 



IN 



PHYSIOLOGY AND HYGIENE 



BY 



J. H. KELLOGG, M. D. 

MEMBER OF THE AMERICAN MEDICAL ASSOCIATION, THE AMERICAN PUBLIC 

HEALTH ASSOCIATION, SOCIETE d'hYGIENE OF FRANCE, BRITISH AND 

AMERICAN ASSOCIATIONS FOR THE ADVANCEMENT OF SCIENCE 

THE AMERICAN SOCIETY OF MICROSCOPISTS, THE AMERICAN 

ASSOCIATION FOR THE ADVANCEMENT OF PHYSICAL 

CULTURE, LATE MEMBER OF THE MICHIGAN 

STATE BOARD OF HEALTH, ETC. 



ILLUSTRATED 











NEW YORK : CINCINNATI . CHICAGO 

AMERICAN BOOK COMPANY 

1894 






Copyriglit, 1894, by American Book Company. 



All right* reserved. 

Kel. 2d Phys. 



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PREFACE. 



In the preparation of this volume the aim of the author has 
been to present only such facts as are of practical value, and 
to arrange these facts in a natural and logical order. 

Those portions of the work devoted to Anatomy have been 
made as untechnical as possible. The author sees no advantage 
in burdening the student with Greek and Latin names for which 
he has no practical use. In accordance with this view, anatom- 
ical names have been used very sparingly. The aim has been 
to teach things rather than names ; and only such anatomical 
facts have been presented as are necessary to a proper under- 
standing of the leading functions of the body. 

From the vast store of facts comprised in the modern science 
of physiology, the author has endeavored to select only those 
which are essential to an understanding of the " reason why " 
in respect to the hygienic precepts inculcated in those portions 
of the work devoted to hygiene. Nevertheless, it is believed 
that the work will be found to contain a more complete state- 
ment of the established truths of modern physiology than any 
other work of its class, as an effort has been made to bring 
within the comprehension of the student a considerable number 
of important facts which have been usually omitted in school 
text-books upon this subject. This is particularly true as re- 
gards the functions of digestion and the physiology of the 
nervous system. It is believed that experienced teachers will 
find the manner in which these subjects are developed of great 
service in clearing away the difficulties which they ordinarily 
present to the average student. 



iv PREFACE. 

In those chapters of the work which are devoted to- Hygiene, 
the author has endeavored to include all essential facts relating 
to individual hygiene suitable for consideration in a work of 
this character, and the treatment of this subject will be found 
unusually full and complete. The author has studiously avoided 
dogmatic statements, endeavoring to give a clear and sufficient 
reason for each hygienic requirement stated. 

Especial attention has been given to that branch of hygiene 
which relates to the abuse of alcohol, tobacco, and other narcot- 
ics and stimulants, and it is believed that no important scientific 
fact relating to this subject has been omitted ; and a number 
of new, and it is believed valuable, facts are presented from 
the results of the author's original researches. 

The attention of teachers is especially called to the numerous 
experiments described in the body of the work and in a sepa- 
rate section, which the author feels assured will assist very 
greatly not only in making clear to the mind of the student the 
subjects illustrated, but in so impressing them upon his mind 
as to greatly assist the memory. The earnest teacher will be 
able to supplement the experiments described by many others 
equally impressive and useful. 

The author gratefully acknowledges large indebtedness to his 
friend Sir B. W. Richardson, M.D., F.R.S., of London, England, 
not only for his laborious researches, which have thrown so 
great a flood of light upon the question of the influence of al- 
cohol upon the human body, but for his kind interest in this 
work and a careful revision and approval of the manuscript. 

It has not been thought best to cumber the text with too 
many illustrations, as the author has prepared a number of col- 
ored charts which illustrate in a very complete manner the sub- 
jects of anatomy, physiology, and hygiene. 

Battle Creek, Mich., April, 1894. J. H. Kellogg. 



CONTENTS. 



OOAP. PAGE 

PREFACE 3 

I. PHYSIOLOGY, ANATOMY, HYGIENE 7 

II. CELLS, TISSUES, ORGANS 9 

III. NUTRITION 16 

IV. FOODS 23 

V. DRINKS 32 

VI. THE ORGANS OF DIGESTION 42 V 

VII. THE DIGESTIVE FLUIDS 49 

VIII. GENERAL VIEW OF THE DIGESTIVE PROCESS 53 

IX. THE HYGIENE OF DIGESTION 58 

X. ALCOHOLIC DRINKS, TOBACCO, AND OTHER NARCOTICS . . 69 

XI. THE BLOOD 97 

XII. THE HEART, BLOOD-VESSELS, AND LYMPHATICS .... 102 

XIII. HOW THE BLOOD IS CIRCULATED HI 

XTV. HYGIENE OF THE HEART, BLOOD, AND BLOOD-VESSELS . . 116 

XV. THE ORGANS OF RESPIRATION 126 

XVI. HOW WE BREATHE 132 

XVII. HYGIENE OF THE LUNGS AND VENTILATION 139 

XVIII. THE VOICE AND THE SPEECH 153 

XIX. THE SKIN AND THE KIDNEYS 156 

XX. HYGIENE OF THE SKIN AND THE KIDNEYS 163 

XXI. BATHING 169 

XXII. CLOTHING 172 

XXIII. THE BONES: THEIR USES, AND HOW TO CARE FOR THEM . 180 

XXIV. HYGIENE OF THE BONES 187 

XXV. ANATOMY AND PHYSIOLOGY OF THE MUSCLES .... 190 

XXVI. HOW TO KEEP THE MUSCLES HEALTHY 198 

V 



vi CONTENTS. 

CHAP. PAGE 

XXVII. THE BRAIN AND THE NERVES . 207 

XXVIII. HOW WE FEEL AND THINK 214 

XXIX. HYGIENE OF THE BRAIN AND THE NERVES 225 

XXX. EFFECTS OF ALCOHOL UPON THE BRAIN AND THE NERVES 231 

XXXI. THE SPECIAL SENSES. — THE SENSE OF TOUCH .... 244 

XXXII. THE SENSE OF SMELL 247 

XXXIII. THE SENSE OF TASTE 250 

XXXIV. THE SENSE OF HEARING 254 

XXXV. THE EYE, AND HOW WE SEE 260 

EXPERIMENTS 271 

QUESTIONS FOR REVIEW 279 

GLOSSARY 290 



SECOND BOOK 

IN 

PHYSIOLOGY AND HYGIENE. 



CHAPTER I. 
PHYSIOLOGY, ANATOMY, HYGIENE. 

1. Physiology. — The ancient philosophers taught 
their pupils in the open air, walking about through the 
fields and groves, and giving instruction concerning the 
various objects they met. This intimate study of nat- 
ure was called by the old Greeks physiology, which 
literally means a discourse upon nature. 

The word physiology is now used in a somewhat dif- 
ferent sense. It is applied to the study of the prop- 
erties, uses, and actions of the various parts of living 
things. Physiology deals with plants and lower ani- 
mals, as well as with human beings ; but our study of 
the subject will be chiefly confined to that department 
of physiology which relates to the human body. 

2. Anatomy. — The body is made up of a great 
number of separate parts, some of which are wonder- 
ful in form, and marvellously intricate and delicate in 
structure. The study of the form and structure of 



8 SECOND BOOK IN PHYSIOLOGY. 

these various parts, and of their relation to each other, 
is called anatomy, 

3. Hygiene. — To maintain the body in health, it is 
necessary that certain conditions should be supplied. 
Hygiene treats of these conditions, and of the rules 
which must be followed to preserve health and vigor. 

One of the most important branches of the study of 
hygiene relates to the avoidance of substances by the 
habitual use of which the delicate structures of the 
body may be injured, and rendered incapable of execut- 
ing in a perfect manner the important duties they are 
intended to perform. Among the most commonly used 
substances of this sort are alcoholic drinks, tobacco, and 
other so-called stimulants and narcotics. Of these sub- 
stances, and their special harmful effects upon the va- 
rious organs of the body, we shall learn in future lessons. 

SUMMARY. 

1. Physiology relates to the properties, uses, and actions of the va- 
rious parts of the body. 

2. Anatomy considers the form and structure of the body. 

3. Hygiene treats of the conditions which are essential for the main- 
tenance of health. 



CHAPTER II. 
CELLS, TISSUES, ORGANS. 

4. Cells. — A drop of water from a stagnant pool, 
when placed under a powerful microscope, is seen to 
contain multitudes of living creatures, some animal and 
some vegetable. Among the numerous living forms is 
found a curious little creature, the amoeba, which looks 
much like a small drop of jelly. It is certainly very un- 
like the creatures familiar to us as animals ; neverthe- 
less it is alive, and may be seen to move about at will. 
It has no limbs ; but when it wishes to move, it puts 
out a foot made for the occasion. It has no mouth, yet 
it can eat. It spreads itself around any tiny morsel of 
food which may happen to come in its way. This curi- 
ous living atom has many remarkable ways and proper- 
ties which we have not space to study. It is sufficient 
for our present purpose to know that it is the simplest 
of all living creatures, the smallest of animals, and that 
it is called a cell. The living, active parts of all animals, 
and of vegetables also, are composed of cells. 

If instead of a drop of pond-water we examine with 
the microscope a drop of blood, w r e shall find in it liv- 
ing jelly -drops, essentially like those found in the pond, 
but smaller. In the brain, the liver, the muscles, the 
bones, — in fact, in every part of the body, — the micro- 
scope shows cells which are in some respects similar to 
those of the pond and of the blood. 
1* 



10 SECOND BOOK IN PHYSIOLOGY. 

All cells are active workers ; and each has its special 
work to do. The human body may be aptly compared 
to a community made up of multitudes of individuals. 
In most communities there are various classes of workers 
— carpenters, blacksmiths, jewellers, chemists, merchants, 
teachers, etc. In the body, likewise, there is a division 
of labor. Some cells build, others tear down. Some 
cells may be compared to artists, others do the work of 
scavengers. Some construct solid parts, others make 
the various fluids to be employed in the body or to be 
removed from it. Some act as sentinels, to give the 
body warning of danger ; others defend it when attacked 
by the enemies of life or health. All labor together in 
the most perfect harmony when their work is not in 
any way interfered with. 

5. Growth. — All living things grow. This is one 
of the characteristic differences between an animal or 
a plant and an inanimate object, as a rock. Masses of 
inanimate matter may be increased in size by the sim- 
ple accumulation of material ; but this is not growth in 
a physiological sense. A plant grows by taking into its 
leaves and roots air, water, and matter in solution, con- 
verting them into its own kind of substance. Animals 
grow in essentially the same way, by # taking food into 
their bodies and converting it into their own structure. 

6. Organs. — A tree has leaves, bark, roots, branches, 
etc., each of which has special properties and uses. So, 
also, an animal has distinct parts, as a mouth, stomach, 
head, legs, and feet, each of which performs some special 
service for the animal. Each part of an animal or a 
plant which has some special work to do is called an 
organ. All animals and vegetables possess organs, and 
are accordingly said to be organized, and to belong to 



CELI.s, TISSUES, ORGANS. 



11 




Fig. 1. — Yellow Fibrous Tissue. 



the organic world. A rock or a mountain possesses no 
organs, and hence belongs to the inorganic world. 
7. The Tissues. — 

Each organ is composed 

of a few simple struct- 
ures, called am atomical 

dements or tissues. The 

whole body is made up 

of these elements, which 

are variously combined 

and arranged to form 

the several organs, just 

as the wood, brick, stone, 

etc., of which a house is 

composed are combined 

in various ways in the 

formation of the various parts of a house. A large part 

of the w r ork of the cells 
of the body consists in 
the development and re- 
pair of these tissues. 

8. Fibrous Tissues. 
— In all parts of the body 
there are found long, 
white, thread-like fibres, 
which are very tough 
and unyielding. This is 
the kind of tissue need- 
ed to bind the different 
parts of the body togeth- 
er, and to make cords 

and protective coverings, for which purposes it is used. 

This is known as white fibrous tissue. 





Fig. 2. — White Fibrous Tissue. 



12 



SECOND BOOK IN PHYSIOLOGY. 






Another form of fibrous tissue, somewhat similar to 
the preceding, but yellow in color, coarser, and capable 
of contracting after being stretched, very much like In- 
dia-rubber, is known as yellow elastic tissue. 

The yellow elastic and white fibrous tissues togeth- 
er form in all parts of the body a finely woven mesh- 
work, called connective tissue. This marvellously strong, 

though delicate, structure 
is found in every organ 
of the body binding to- 
gether the various tis- 
sues, forming sheaths, 
membranes, bands, 
pouches, coverings, and 
thus serving everywhere 
purposes of protection 
and support. 

9. Adipose Tissue. — 
In some parts of the body 
the meshes of the con- 
nective tissues are occu- 
pied by cells which are filled with fat. This is adi/pose 
tissue. This soft tissue forms cushions for delicate or- 
gans like the eye, rounds out the form, and serves sev- 
eral other very useful purposes. 

10. Osseous Tissue. — A very dense tissue, the hard- 
est in the body, forms the chief part of the bones, from 
which it is known as osseous tissue. This tissue is strong- 
er than the toughest oak. 

11. Cartilage Tissue. — Some organs require a 
tissue having something of the rigidity of the bones, and 
at the same time capable of yielding or bending a little 
under pressure. This requirement is met by the carti- 




Fig. 3. — Connective Tissue. 



CELLS, TISSUES, ORGANS. 13 

lage tissue. Most cartilages arc connected with hones, 
which are themselves at iirst composed of this kind of 
tissue. In old age, many of the cartilages of the body 
become bony in character. 

12. Muscular Tissue. — Those portions of the body 
which correspond to the lean meat of animals are made 
up of muscular tissue. Muscular tissue is composed 
of minute fibres, each of which is able to shorten and 
lengthen somewhat as an earthworm contracts and ex- 
tends its body when in motion. 

13. Nervous Tissue. — The brain and nerves are 
composed of cells and fibres possessed of properties the 
most remarkable to be found in living creatures. These 
cells and fibres constitute nervous tissue. 

14. Epithelium. — Covering the whole surface of the 
body, and lining all its cavities, are found layers of curi- 
ous cells. In one locality these cells assume one form, 
and in another a very different one. They are called 
epithelial cells, and the covering which they help to form 
is called epithelium. 

15. Tissue-builders. — As we have learned, all of 
the various tissues are built and maintained by living 
cells. Life depends immediately upon the proper and 
continuous activity of these cells. Anything which im- 
pairs their vigor or hinders their activity, injures health 
and threatens life. Hence we should make a careful 
study of our bodies, and should endeavor to ascertain 
how best to maintain in health and vigor the vast army 
of little workers which carry on within them the various 
operations upon which life depends. 

16. Tissue-destroyers. — There are numerous sub- 
stances which, when taken into the body, exert a most 
damaging influence upon the delicate tissues of which 



14 SECOND BOOK IN PHYSIOLOGY. 

it is composed. Among the most harmful of these are 
alcohol and tobacco. Alcohol, in particular, occasions 
very great mischief. When brought into immediate con- 
tact with any of the tissues, it produces at first paraly- 
sis, then death. When taken in the form of alcoholic 
drinks, the injurious effects appear less quickly, but none 
the less surely. Every tissue of the body is injured. 
Many of the tissues are so changed that they lose their 
natural properties, and are hardly recognizable. These 
facts have been ascertained by numerous experiments 
upon animals, and by examinations made after death 
in cases of persons who had been addicted to the use 
of alcoholic drinks. 

17. Effects of Alcohol upon Connective Tissue. 
— Alcohol is an irritant, and produces a harmful change 
in the connective tissue of various parts of the body, 
especially that of the liver and the brain. There is at 
first an increased growth of the connective tissue. Then 
the overgrown tissue contracts, and becomes hard and 
unyielding, like a scar. As a result, the delicate struct- 
ures which the connective tissue should protect are com- 
pressed so as to injure them greatly, and finally they 
may be completely destroyed. This change is some- 
times almost universal in the body of a drunkard. 

18. Effects of Alcohol upon the Tissue-builders. 
— Still another charge which may be fairly brought 
against alcohol, is that it lessens the activity of the 
tissue-building cells, and when taken in a concentrated 
form, may paralyze them completely. This is one reason 
why a person who uses alcoholic drinks recovers less 
rapidly from an accident than does one who abstains 
from the use of this drug, a fact which has been noticed 
and remarked by many eminent surgeons. 



CELLS, TISSUES, ORGANS. 15 

19. Effects of Tobacco upon Tissue - building 
Cells. — Tobacco has a similar effect upon the cells 
which build and repair the tissues. This is the reason 
why the use of tobacco stunts the growth and prevents 
the proper development of a boy who begins its use at 
an early age. It is for this reason that all physicians 
agree that the use of tobacco by young persons is most 
pernicious in its effects. 

Opium and other narcotic drugs affect the tissue-build- 
ers in essentially the same manner, and hence are dan- 
gerous enemies to health and life. 

20. Health and Disease. — When all the cells and 
organs of the body are acting properly and harmonious- 
ly, an individual is said to be in a state of health. When 
for any cause an organ ceases to act, or acts in an un- 
natural or disorderly manner, the individual suffers dis- 
comfort, and is said to be in a state of ill-health, or dis- 
ease. The causes of disease affect the body harmfully 
through their influence upon its living cells. 

SUMMARY. 

1. All living things are composed of cells, to which their activities 
are due. 

2. Through the action of their cells, animals and plants groic. 

3. Animals and plants have organs, and hence are organized. From 
this we have two classes of objects in nature, organic and inorganic. 

4. The ultimate elements of which the body is composed are called 
tissues, of which there are six, fibrous, adipose, osseous, cartilage, muscu- 
lar, nervous. 

5. The tissues are built and repaired by cells. 

6. Certain substances, particularly alcohol, tobacco, opium, and other 
narcotics, when taken into the body, paralyze the tissue-builders, and 
destroy the tissues. 

7. The harmonious activity of all the bodily organs constitutes 
health. A state of disorder in the body is disease. 



CHAPTER III. 
NUTRITION. 

21. Wastes and Losses of the Body. — Just as a 
steam-engine in doing its work gives off smoke and ashes, 
and loses steam and heat, so every movement of the body 
results in waste from the wearing out of the tissues and 
the using up of materials. Every movement of the limbs 
in walking or running, every motion of the hands or 
arms, the smallest movement of a finger, the beating of 
the heart, or even the winking of an eye, causes waste or 
loss of substance. 

22. Amount of Bodily Wastes. — The amount of 
waste or loss depends chiefly upon the kind and amount 
of work performed, just as with a locomotive engine the 
amount of steam, smoke, and ashes lost depends upon 
the speed at which it runs and the load it has to draw. 
That the loss is considerable is seen in the fact that when 
deprived of food the body rapidly diminishes in weight, 
usually at the rate of several pounds daily. 

In addition to the loss of tissue substance, the body 
sustains certain other losses, the most important of 
which are of water and heat. Water is lost chiefly in 
connection with the removal of waste substances. Be- 
sides that which is removed through the bowels and 
the kidneys, water is constantly passing off through the 
lungs and the skin, in the form of an invisible vapor. 
The moisture of the breath becomes visible when one 



NUTRITION 17 

is breathing in the open air on a frosty morning; and 
when one exercises violently, or is exposed to extreme 

heat, the water thrown off by the skin becomes visi- 
ble in the form of sensible perspiration, or sweat. The 
amount of water lost daily is three or four pints. 

23. Excretion. — The removal of waste products 

from the body is called excretion, and is one of the 

most important of all the vital processes. The organs 

'by which this work is accomplished are the lungs, liver, 

bowels, skin, and kidneys. 

2-t. Loss of Heat. — The temperature of the body is 
constantly maintained, during life, at a little less than 
100° Fahr. A thermometer held in the mouth for a 
few minutes indicates 98±-° Fahr. The constant forma- 
tion of heat within the body makes it necessary that 
heat should be continually given off, to prevent the 
temperature of the body from becoming too high. In 
cool or cold weather, heat is given off chiefly by the 
contact of the body with the surrounding air; in very 
hot weather, the body is cooled by the evaporation of 
moisture from its surface. 

25. Repair of Wastes and Losses. — Nature has 
made provision for the prompt repair of wastes, so that 
under ordinary circumstances, in a state of perfect health, 
each loss is made good almost as soon as it occurs. The 
process of repairing wastes is known as assimilation. 
Each tissue possesses the power to take from the blood 
the elements necessary to replace those which it has lost 
through the wear and tear of bodily work. In infancy 
and childhood, assimilation overbalances waste, so that 
the individual increases in size. In grown persons the 
two processes are evenly balanced, and the body neither 
gains nor loses. In old age, waste overbalances assimi- 



18 SECOND BOOK IN PHYSIOLOGY. 

lation, and so the body gradually grows weaker and 
smaller, until death occurs from disease or a general 
wearing out of the system. The reverse of assimila- 
tion, or the breaking down of the tissues, is known as 
disassimilation or disintegration. 

26. Glands. — Much of the work connected with the 
repair of the tissues and the removal of waste matters is 
performed by a very remarkable class of organs, called 
glands. A gland is an organ which makes from the 
blood a fluid peculiar to itself and very unlike the blood. 
If the fluid thus formed is intended for use in the body, 
it is called a secretion; if it is intended to be removed 
from the body, it is called an excretion. The saliva is a 
secretion ; the perspiration, or sweat, an excretion. 

The structure of glands is very interesting. The sim- 
plest gland is merely a little pouch in the skin or mucous 
membrane, lined with cells capable of making some spe- 
cial fluid. In more complicated glandular structures we 
find two or more pouches with a common opening. In 
large glands we have a large number of these pockets or 
pouches gathered together in a single mass, and pouring 
the product of their work into a common canal, called a 
duct. 

27. The Materials Needed for Repair of Wastes 
and Losses. — The constant loss of matter from the 
body makes it necessary that a regular supply of new 
material should be received. The system requires three 
classes of substances to supply all its needs : 1. Organ- 
ized material, in the form of vegetable or animal sub- 
stances ; 2. Water, a liquid ; 3. Oxygen, a gas. In future 
chapters we shall learn how these necessary materials 
are introduced into the body, and shall study the differ- 
ent processes by which the body makes use of them. 



NUTRITION. 1!) 

98. The Hygiene of Nutrition. — In order thai the 
body shall be maintained in health, it is necessary thai 

a proper balance between waste and repair should be 
maintained. The necessary materials to make good the 
losses of the body must be supplied in proper quantity. 
The waste and poisonous substances formed within the 
body must be promptly removed, and substances of a 
poisonous character must be carefully excluded. 

29. Alcohol, Tobacco, and Opium. — Among the 
most dangerous of all enemies to health and life are 
all kinds of alcoholic drinks, tobacco, and the different 
preparations of opium. When any of these poisons 
are taken into the body, they come in contact with 
the delicate cells which do the various kinds of work 
that are carried on in the body. All stimulants and 
narcotics injure these cells, interfere with their work, 
and thus do great mischief, often inflicting irreparable 
injury. 

30. The Effects of Alcohol and Tobacco upon 
Nutrition. — Although we are not yet prepared to en- 
ter fully upon the study of the effects of these sub- 
stances upon the body, it will be proper for us to notice 
briefly the harmful effects of some of them upon the 
general nutritive processes of the body. 

Numerous experiments, made by eminent scientists at 
different times and in various countries, show conclu- 
sively that when any considerable amount of alcohol is 
taken into the body, almost the entire amount reappears 
in the excretions without having undergone any change 
like that which takes place in food. That is, alcohol 
reappears in the breath and other excretions as alcohol, 
or in the form of some substance so nearly like alcohol 
that it is easily recognized as being derived from it. A 



20 SECOND BOOK IN PHYSIOLOGY. 

very small amount of alcohol disappears in the body, 
but it has never been proved that any useful purpose is 
served by it. Alcohol not only does not make good the 
wastes of the body, but is a clog and hinderance to the 
delicate vital organs ; for these organs are not only in- 
jured and weakened by it, but must devote to the work 
of removing the alcohol, energy w^hich should be ex- 
pended in removing waste substances. 

A proof that alcohol injures the body in this way 
may be seen in the bloated appearance of a beer-drink- 
er. His system is filled with impurities which should 
have been carried out of the body, but which have been 
retained because the organs of excretion have been em- 
ployed in removing the alcohol and other impurities con- 
tained in beer. His blood is impure. He is, on this ac- 
count, an easy prey to disease, and if he happens to suffer 
an accident, he is more liable to die than if he abstained 
from the use of alcoholic drinks. 

But alcohol disturbs the processes of nutrition in other 
ways. It hinders assimilation, and destroys that nice 
balance between waste and repair upon which the health 
and symmetry of the body depend. This is often very no- 
ticeable in some portions of the face, particularly in the 
nose, which under the influence of alcohol, becomes red 
and inflamed in appearance, and often grows to be too 
large for the rest of the face. This condition is so char- 
acteristic of intemperance that such a nose is sometimes 
called a "rum blossom." 

31. Effects of Tobacco and Opium upon Nutri- 
tion. — Tobacco and opium, as well as alcohol, disturb 
the processes of nutrition, although the effects are not 
precisely the same. These poisons, when taken into the 
body, must be removed. They cannot possibly serve any 



NUTRITION". 21 

useful purpose. They paralyze the tissue-builders, and 
hence their influence is most pernicious. The delicate 
organs by which the important processes of life are car- 
ried on are hindered in their work, being required to ex- 
pend much effort in removing from the body the nox- 
ious intruders. The breath, and all other excretions of 
a tobacco-user, are tainted w T ith the poison, showing that 
his body is saturated with it. 

Tobacco, opium, alcohol, and all other poisonous sub- 
stances, endanger health when taken into the body, by 
lessening the activity of the special cells which have for 
their duty the defence of the system against those most 
powerful of all the foes of human life and health, micro- 
scopic germs. These unseen agencies of disease and 
death are constantly about us. They float in the air as 
fine dust; they abound in water not obtained from the 
purest sources ; and they are constantly present in va- 
rious articles of food. Germs would quickly destroy 
our lives were it not for the fact that the body is sup- 
plied with a special class of cells, found chiefly in the 
lungs, the intestines, and the blood, which are capable 
of destroying germs, and thus defending the body 
against them. Tobacco, opium, alcohol, and other 
poisons paralyze these germ-destroying cells, and thus 
render the body defenceless against the attacks of dis- 
ease germs. 

We may learn many useful lessons in hygiene by the 
study of the lower animals. These creatures, so much 
inferior to human beings in intellect, are, in their habits 
of life, led chiefly by instinct. Their instincts being less 
perverted than are those of human beings, their natural 
appetites are more reliable guides than are ours. This 
is not because man was made inferior to lower animals 



22 SECOND BOOK IN PHYSIOLOGY. 

in this respect, but because by long yielding to unnatu- 
ral appetites, and following harmful customs, his natural 
instincts have become perverted. 

An instructive illustration of this principle is found 
in the fact that no lower animal, in a natural state, in- 
dulges in the use of substances which correspond in ef- 
fects to the narcotics and stimulants so extensively used 
by human beings. This is not because lower animals 
are not affected by these drugs in the same way as are 
human beings, for it is well known by physiologists 
that, with a few rare exceptions, the effects of narcotics 
and stimulants on man and lower animals are essentially 
identical. A goat was once made drunk by some mis- 
chievous sailors, but afterwards ran away whenever ap- 
proached by those who had once imposed upon him. It 
would be well if human beings always showed an equal 
amount of wisdom. 

SUMMARY. 

1. All vital toork is accompanied by waste. 

2. Bodily wastes consist in loss of tissue substance, water, and heat. 

3. The removal of wastes is called excretion. 

4. Tissue-building is called assimilation; tissue waste, disassimilation 
or disintegration. 

5. Needed for nutrition — food, water, and air. 

6. Needed for health — regular and sufficient supply of food, water, 
and air, and the prompt removal of wastes. 

7. The most serious disturbers of nutrition are stimulants and nar- 
cotics — alcohol, tobacco, opium. 

8. Alcohol clogs the tissues, hinders assimilation, and disturbs the 
balance of the nutritive functions. 

9. Tobacco and opium clog the tissues and paralyze the tissue- 
builders. 

10. No lower animal naturally uses narcotics or stimulants. 



CHAPTER IV. 
FOODS. 

32. What are Foods? — In the preceding chapter 
we have learned that the body is constantly sustaining 
Josses in consequence of the vital work performed by 
its various organs. Foods are substances which, when 
introduced into the body, make good its natural wastes 
and losses, and furnish proper material for the repair of 
its tissues, or for carrying on its vital processes. As we 
have already learned, these requirements are met by 
organized matter, water, and ox} T gen, or what may be 
termed solid, liquid, and gaseous foods. Of these, the 
first only is commonly known as food. Liquid foods 
are called drinks, all of which have water for their es- 
sential element. In this chapter our attention will be 
confined to the consideration of organized foods. 

A poison is the opposite of a food. It not only does 
not repair wastes and losses, but interferes with the vital 
processes, disturbing them in such a way as to occasion 
sickness and death. 

33. Animal and Vegetable Foods. — Man employs 
both animal and vegetable substances as foods. Some 
nations, particularly the English people and Americans, 
use a large proportion of flesh, and some barbarous 
tribes live almost wholly upon the flesh of animals ; but 
the larger portion of the human race live chiefly upon 
vegetable foods. Many millions of human beings in 



24 



SECOND BOOK IN PHYSIOLOGY. 



India and other parts of Asia never taste flesh, consider- 
ing it a sin to do so. 

34. Plants the only Food - producers. — Plants 
alone possess the power to construct living substance out 
of the elements of the earth and the air. Animals are 
able to subsist upon organized substances only, so that a 
lion, in dining upon an antelope, is only eating at second 
hand the grass and herbs which the latter has eaten ; 
and a man, in eating roast beef, is taking at second hand 
the corn upon which the ox was fed. 

35. Food Elements. — When a chemist examines a 
loaf of bread or a piece of meat, he finds it to be made up 
of various substances quite unlike each other, each pos- 
sessing peculiar properties, and destined for different uses 
in the body when taken as food, called food elements. 

36. Classification of Food Elements.— The various 
substances found in foods may be included in six classes : 
1. Starch ; 2. Sugars ; 3. Albumen (all albuminous sub- 
stances) ; 4. Fats; 5. Salts; 6. 
Indigestible Elements. 

37. Starch. — This element 
is found only in vegetable 
foods. In a raw state, starch 
is found in small particles or 
granules, each enclosed in a 
w r oody envelope. Starch is 
the most abundant of all the 
food elements. (See Experi- 
ments 1 and 2, page 271.) 

38. Sugar. — Sugar is very 
unlike starch in its general 

properties, although closely related to it. In the mys- 
terious chemistry of plant life, the insoluble, tasteless 




Fig. 4. — Potato Starch. 



FOODS. 



25 




Fig. 5. — Starches. 



starch is converted into this sweet and extremely solu- 
ble substance. Several different kinds of sugar occur 
in nature, the most important 
of which are <?<m<?-sugar, grape- 
sugar, and milk-sugar. 

Cane-sugar is the sweetest 
of all the sugars, and is that 
commonly used as food. It 
is obtained from the sugar- 
cane, the sorghum plant, the 
beet root, and the maple-tree. 
Grape-sugar is found in most 
fruits and in honey. Milk- 
sugar gives to milk its sweet- 
ness. A sugar resembling 

grape-sugar, called glucose, is very extensively manufact- 
ured chemically, by boiling the starch of corn or pota- 
toes with sulphuric acid. Glucose cannot be considered 
a perfect substitute for natural sugar. 

39. Albumen. — The white of an egg is almost pure 
albumen. All true foods contain elements which in 
many respects resemble albumen and serve the same 
purposes in the body, and so are termed albuminous ele- 
ments. For convenience, we shall apply the term al- 
bumen to any or all of them. The lean portion of flesh 
and the caseine of milk are forms of animal albumen. 
All vegetable foods also contain albumen. Caseine, for 
example, is found in peas and beans, as well as in milk. 
One of the most important of all the albumens is gluten, 
which is found in wheat, rye, and barley. 

40. Fats.— Oil, or fat, is found in both animal and 
vegetable foods. The principal animal fats used as food 
are butter, lard, suet, and tallow. Vegetable oils are 

2 



26 SECOND BOOK IN PHYSIOLOGY. 

chiefly derived from oily fruits, as the olive, from nuts, 
and from various seeds. A very considerable quantity 
of fat is found in corn and oats. 

41. Salts. — When a portion of animal or vegetable 
food is burned, there is left a residue of ashes, made 
up of inorganic or mineral elements. These are the so- 
called salts of the food. They do not exist in the food 
in the form in which they are found in its ashes, but in 
an organized form. The most important source of salts 
is the grains. Wheat, oats, barley, corn, and rye contain 
an abundant supply of this element, as do the potato 
and most other vegetables. The salts also exist in 
milk in good proportion. 

42. Indigestible Elements. — All vegetable foods 
contain more or less of a woody substance, called cellu- 
lose. The bran of wheat belongs to this class of ele- 
ments. Cellulose is not to any extent digestible, but it 
serves an important purpose in giving bulk to the food. 
The connective tissue elements of flesh foods — the liga- 
ments, tendons, etc. — are hard to digest, and afford little 
or no nourishment. 

In addition to the several elements mentioned, all 
food substances contain certain flavoring matters. 

43. Condiments. — A condiment is an article which 
possesses little or no food value, but is added to food 
for the purpose of imparting to it a characteristic flavor. 
The condiments most commonly used in this country 
are mustard, pepper, ginger, spices, pepper-sauce, Worces- 
tershire and other hot sauces, and vinegar. All condi- 
ments possess irritating or stimulating qualities. They 
stimulate the appetite, and act as whips to the stomach 
and other digestive organs, and are thus injurious. 

44. Food Substances. — The several food elements 



FOODS. 27 

which we have been considering are not, in any proper 
sense, to be regarded as food. An animal fed exclusive- 
ly upon any one of them soon acquires such a disgust 
for its food that it will refuse to taste it, even though 
starving, and sooner or later dies. Gluten is the only 
exception to this rule. A true food contains various 
elements, which are combined in varying proportions in 
different foods. Let us now briefly notice some of the 
leading food substances. 

45. Foods of Animal Origin. — Chief among animal 
foods is milk, the natural diet of most young animals. 
Milk contains the elements of nutrition in proper pro- 
portion, and will sustain life for an indefinite period. 
The chief albuminous element of 

milk is caseine. The white color 
of milk is due to the fact that it 
contains a considerable amount of 
fat or oil in' a state of emulsion, 
or division into minute drops. 
When milk is allowed to stand 
for a few hours, the oily particles 
collect at the top, constituting 
the cream. By churning, the lit- Fig. 6.— Milk Globules. 
tie drops are made to unite, pro- 
ducing butter. The ease with which it is digested ren- 
ders milk a most suitable food for the young. It is, in- 
deed, with rare exceptions, a most wholesome food for 
persons of all ages. 

46. Cheese is made from milk by adding rennet, 
which separates the caseine and fat from the whey. 
Cheese undergoes partial decomposition in the process 
of " curing," and is on this account much less whole- 
some than fresh milk. It is difficult to digest, and 




28 SECOND BOOK IN PHYSIOLOGY. 

likely to interfere with the digestion of other foods. 
Sometimes a peculiar fermentation takes place in cheese, 
which produces a very poisonous substance, known as 
tyrotoxicon. Very serious and sometimes fatal illness 
often results from the use of such cheese. This poison 
is destroyed by heat. On this account cheese is ren- 
dered less dangerous by cooking, while at the same time 
it is also made more digestible. 

47. Flesh. — The flesh of the ox, sheep, or hog, is 
more largely used as food in this and most other civil- 
ized countries than any other kinds of flesh food. Mut- 
ton is not so well relished by some, but is nearly as nour- 
ishing as beef and equally easy to digest. Pork contains 
much fat, is difficult to digest, is likely to be diseased, and 
must be regarded as an inferior food. The Jews in an- 
cient times were forbidden to eat the flesh of the hog, 
and still abstain from the use of pork, doubtless for 
good reasons. The flesh of deer and other wild game, 
while usually less tender than that of stall-fattened ani- 
mals, is more wholesome if eaten when fresh, on account 
of the healthier conditions of life which wild animals 
usually enjoy. Game is often allowed to become almost 
putrid before it is eaten. Such flesh is exceedingly un- 
wholesome. Veal, like the flesh of all very young ani- 
mals, is difficult to digest, and can not be recommended 
as food. 

48. Fish and Fowl. — The nutritive value of fish 
and fowl is not quite equal to that of beef or mutton, 
but when properly cooked they are relished by most 
persons, and possess considerable value as foods. 

49. Shell-fish contain very little nutriment, although 
some of them, oysters in particular, are in very great 
favor as table delicacies. All shell-fish are scavengers, 



FOODS. 2!) 

however, and are sometimes poisonous. Frogs, lobsters, 
shrimps, sea-crabs, etc., are by many considered delicate 

eating, but can not be regarded as really first-class foods. 
The oyster is easily digested, though it does not possess 
the power to digest itself, nor to aid digestion when 
eaten raw, as many persons suppose. The oyster is a 
scavenger in its habits, and when the beds in which 
oysters grow are located in such a manner as to be 
reached by the impure matters carried into the sea by 
the sewers of a large city, they sometimes become dis- 
eased, and produce serious illness when eaten. 

50. Eggs. — An egg contains within itself every ele- 
ment needed for the support of the body, and has the 
advantage, when properly cooked, of being one of the 
most easily digested of foods, and one of very high 
nutritive value. 

51. Salted and Smoked Meats. — Most kinds of 
flesh foods are preserved by salting. The process of 
salting hardens the tissues and renders them difficult 
to digest. Smoked meats and fish are also hard to 
digest. 

52. Vegetable Foods. — Vegetable foods are the 
original source of the nutritive elements contained in 
flesh foods ; hence we should expect them to furnish all 
the elements of nutrition, and in good proportions. This 
is the case with the best vegetable foods. 

53. Fruits, Grains, Vegetables. — Vegetable foods 
are usually divided into three classes— -fruits, grains, and 
vegetables. Fruits comprise fleshy seeds and seed-bear- 
ing portions of plants, such as the apple, strawberry, 
and plum, each of which represents a different class of 
fruits. Melons and nuts are also fruits. The grains 
comprise those seeds used as foods which are produced 



30 SECOND BOOK IN PHYSIOLOGY. 

by grass -like plants, as wheat, oats, rye, barley, corn, 
and rice. Allied to this class are the edible seeds of 
pod-bearing plants, the chief of which are peas, beans, 
and lentils. The grains are the most nourishing of all 
foods, and contain the elements of food in the best pro- 
portion. Fruits, grains, and milk constitute a perfect 
dietary, and one particularly suitable for young per- 
sons, and for students and other brain-workers. 

Those parts of plants used as food, other than seeds 
or fruits, such as leaves, stems, roots, buds, and flowers, 
are called vegetables. The nutritive value of vegeta- 
bles is much less than that of grains. The potato, one 
of the most valuable of all vegetables, is three-fourths 
water, and contains only about two per cent, of albumi- 
nous elements. The starch of vegetables is more diffi- 
cult to digest than that of grains and fruits, and the 
large amount of woody matter contained in most vege- 
tables adds to their indigestibility, so that they must be 
regarded, in general, as much inferior to fruits and grains 
as foods. 

54. The Natural Diet of Man. — It is probable that 
the diet of the human family at first consisted almost 
wholly of fruits, grains, milk, and a few vegetables. 
History informs us that the dietary of the ancient 
Egyptians, Assyrians, and the early Greeks and Romans 
was of this simple character, and the same primitive diet 
is still practically adhered to by fully two-thirds of the 
inhabitants of the globe. In densely populated coun- 
tries, such as Japan and China, the dietary is necessa- 
rily almost exclusively vegetarian in character. The 
peasantry of France, Italy, and Spain, and other con- 
tinental European countries, employ flesh so sparingly 
in their dietary that they may be said to use it as a 



FOODS 31 

luxury rather than as a food. Euman life and health 
may be well maintained upon vegetable Food. 

55. Uses of the Several Food Elements. — The 

various food elements serve different purposes in the 
body. Sugar, starch, and fat form adipose tissue, and in 
the form of fat enter into the composition of nearly all 
the tissues of the body. They are of essential service 
to the body in the production of heat and force. The 
different forms of albumen nourish especially the brain, 
nerves, muscles, glands, and other highly active tissues 
of the body. The salts are largely used in nourishing 
the bones. They are also required by the brain and 
the nerves, as well as by other tissues. The indigesti- 
ble elements give necessary bulk to the food. 

SUMMARY. 

1. Foods suppty material to replenish the tissues or to support the 
vital functions. 

2. A. poison is a substance which is not a food, and which is injuri- 
ous to the body. 

3. Man and other animals subsist upon organized food. 

4. Plants are the only real food producers. 

5. There are six food elements — starch, albumen, fats, sugars, salts, 
and indigestible elements. 

6. Condiments are flavors, not foods, and generally harmful. 

7. Starch, sugars, and fats nourish adipose tissue, and maintain heat 
and force. 

8. Albumen nourishes the active tissues, especially the muscles, 
brain, and nerves. 

9. The salts nourish the bones and the nerve tissues. 

10. The indigestible elements give necessary bulk to the food. 



CHAPTER V. 
DRINKS. 

56. Water is the only substance that will quench 
thirst. Other drinks consist of solids dissolved in water. 
The importance of water may be inferred from the fact 
that it constitutes more than three-fourths of the entire 
weight of the body. 

57. Uses of Water. — Water is of service to the 
body chiefly in the following ways : 1. To soften the 
food in its preparation by cooking ; 2. To carry the dis- 
solved food in the blood to the various parts of the body ; 
3. To dissolve and remove the waste elements of the tis- 
sues ; 4. To carry away by evaporation from the sur- 
face any excess of heat which may be generated, thus 
regulating the temperature of the body. 

58. Pure Water. — Absolutely pure w^ater does not 
exist in nature, but may be obtained by distillation. 
Ordinary water contains air and other gases, together 
with various substances derived from the air and the soil. 
Some of these substances are harmless ; others are very 
injurious when taken into the system in any but very 
small quantities. 

59. The Impurities of Water. — Dangerous sub- 
stances, when present in water, are chiefly derived from 
the soil. These impurities are of two kinds, inorganic 
or mineral matters, and organic or organized substances. 

Inorganic impurities are chiefly made up of various 



DRINKS, 
compounds of Lime, magnesia, soda, potash, iron, etc., 

and chloride Of sodium, or common salt. The sails of 
lime and magnesia cause water to be hard, and show 
their presence by forming a curd with soap. 

60. Mineral Matters. — Mineral waters are usually 
obtained from springs or artesian wells, and contain an 
unusually large proportion of inorganic impurities, some- 
times amounting to several ounces per gallon. As a 
rule, the continued use of mineral water, notwithstand- 
ing the benefit which may be derived from its temporary 
or occasional use, is in some measure detrimental to 
health. 

61. Poisoning from Lead or Zinc. — Lead pipes 
are objectionable for the conveyance of water which is 
to be used for cooking or drinking purposes. If one is 
temporarily obliged to use water from lead pipes, the 
danger of poisoning may be greatly lessened by allow- 
ing the water to run until that which has stood in the 
pipe has escaped, and fresh water has entered from the 
street main. 

Lead poisoning sometimes occurs from the use of 
cooking utensils made of a poor quality of tin contain- 
ing lead. Some foods, and especially acid fruits, acquire 
poisonous properties when cooked in zinc or galvanized- 
iron vessels. The prominent symptoms of lead poison- 
ing are chronic pains in the bowels, inactive bowels, loss 
of appetite, wrist drop, and a blue line at the edge of 
the gums. 

62. Germs. — The organic and organized matters 
found in impure water consist of decomposing animal or 
vegetable substances, and various forms of microscopic 
life. Of the latter, the most important, because the most 
dangerous to life, are certain minute organisms known 

9* 



34 



SECOND BOOK IN PHYSIOLOGY. 



as germs. Although the smallest of all living forms, 
germs are the most destructive and dangerous of all 
enemies to life and health. Their power for mischief 
depends chiefly upon two things : 1. Their ability to 




Fig. 7. — A Drop of Impure Water. (Magnified.) 



manufacture poisons of a peculiarly deadly character; 
2. The amazing rapidity of their development. Some 
germs, under favorable conditions, double in number 
every fifteen minutes. Estimate the number which, at 
this rate, might arise from a single germ in twenty-four 
hours ! All processes of fermentation, decay, and putre- 
faction, in animal and vegetable substances, are set up 
and carried on by different species of germs. Germs 




z 






O 1 

LU ,T 

h- ^ 

o 



f : igni 




I ; - '■ '' : teg 


tt 


S*lsSSI 




|if@si 


*■ *■ 




Hf^ & 




AlSikSl mm&- sag 



l@ffl 




34— A. 



DRINKS. 35 

are thus of immense service in reducing to dust the 
dead bodies of plants and animals. 

Typhoid-fever, cholera, yellow-fever, and many other 
infectious, or " catching," diseases are produced and com- 
municated by germs. These organisms are possessed of 
great vitality. The extreme cold of the Arctic regions 
does not destroy them. They may be widely scattered 
in bodies of water, or dispersed in the air in a dry state, 
and yet retain their destructive properties. Great care 
should be taken to avoid contact with any person suffer- 
ing from a contagious or infectious disease. Such per- 
sons should be separated from all others except the nec- 
essary nurses, and disinfectants should be used under 
the direction of a physician. By this means the spread- 
ing of contagious diseases may be prevented. 

63. Sources of Organic Impurities in Water. — 
The chief sources of organic impurities in well-water are 
vaults, cesspools, and drains. These reservoirs of filth 
frequently saturate the earth to a considerable distance 
around them. Water falling in rains soaks into the 
earth, and in passing through the soil becomes contami- 
nated. At length it finds its way into wells near by. 
Dug wells are constantly being poisoned in this manner. 

A cesspool or vault which is not perfectly water-tight 
— and one which is made water-tight is certain to leak 
sooner or later — may at any time contaminate a well 
which is located on the same or an adjoining village lot 
of ordinary size, and may even extend its poisonous in- 
fluence much farther. This remark refers, of course, to 
dug wells, which always receive more or less surface- 
water. Any considerable mass of decomposing matter 
near a well is a source of danger. 

Dead animals buried near a well, or decomposing mat- 



36 SECOND BOOK IN PHYSIOLOGY. 

ters upon the surface, may be a source of contamina- 
tion. It is also believed that the water of wells in the 
vicinity of cemeteries is not infrequently poisoned by 
them. Cistern-water is sometimes contaminated by cess- 
pools or leaking drains, or by sewers through connecting 
overflow pipes. Water stored in wooden tanks or casks 
soon becomes quite impure. 

Bain-ivater usually contains more or less organic mat- 
ter. The first rain that falls at the beginning of a show- 
er washes from the roof dust and other filth which has 
been deposited upon it. In falling through the air, the 
rain also collects germs and microscopic forms of life, 
dust, fragments of insects, soot, etc. Cistern-water usu- 
ally contains sufficient organic matter to support multi- 
tudes of low forms of life. Spring-water, as well as the 
water of wells, may be contaminated by decomposing 
matter from the immediate vicinity or from a distance. 

The water of streams, lakes, and indeed all natural 
waters, are more or less liable to contamination. 

64. Impure Ice. — Ice formed upon impure water is 
also impure, and often becomes a source of serious dis- 
ease. Ice collected from stagnant ponds, or from rivers 
or small lakes into which sewers empty, should never 
be used for drinking purposes, nor in food refrigerators. 

65. To Detect Bad Water. — Pure water is color- 
less, odorless, and tasteless ; but water may be danger- 
ously contaminated and yet be colorless and odorless, 
and have no perceptible flavor. Dangerous impurities 
may usually be detected by the following simple method : 

Nearly fill a clean two-ounce vial with water to be 
tested. Add a small lump of pure white sugar. Cork 
and put in a warm place. If the solution becomes tur- 
bid in a few days, the water is unwholesome. 



DRINKS. 37 

66. Bad Effects of Impure Water. The use, for 
a considerable time, of water containing inorganic im- 
purities, as very hard water, produces different forms 
of dyspepsia, and disorders of the liver, kidneys, and 
bladder. Organic impurities in water may give rise 
to a large number of serious and even fatal maladies. 
Typhoid-fever, cholera, dysentery, and other dangerous 
diseases are spread by the use of contaminated water. 

Intestinal parasites are sometimes introduced into the 
body through impure water containing their embryos or 
eggs. River- water is especially liable to contamination of 
this sort, and should never be used without boiling, even 
if chemical tests show no evidence of organic impurities. 

Most physicians have met with cases in which persons 
have suffered long and dangerous and even fatal illness 
from using contaminated water. Not long ago more 
than a thousand persons living in a small town in Penn- 
sylvania were stricken down with typhoid-fever. The 
epidemic was traced to contamination of the drinking- 
water from a single case of the disease. Sometimes the 
infection is conveyed by milk which has been adulter- 
ated with foul water. The washing of milk-cans with 
foul water may infect the milk, and render it capable of 
exciting typhoid-fever and other diseases. An epidemic 
of typhoid-fever occurred in the State of New York, 
which was traced to the use of milk from a dairy in 
which the milk cans were wiped with cloths which hung 
in a room next to one in which was a patient sick with 
this disease. It is probable, also, that cows may become 
infected through the drinking of impure water, and thus 
communicate it to human beings through milk ; hence 
the same care should be taken to secure pure water for 
domestic animals as for human beings. 



38 SECOND BOOK IN PHYSIOLOGY. 

67. Purification of Water. — Water which is known 
to be dangerous to health on account of contamination 
with organic matter should be avoided altogether. Wa- 
ter which is only slightly impure may be cleansed by 
first boiling thoroughly and then filtering. Always boil 
water suspected of being impure. The boiling will de- 
stroy animalcules and germs, and proper filtration will re- 
move decomposing matter and sediment. Filters are of 
little use, however, unless made of good vegetable or 
animal charcoal. Those made of sand and porous stone 
simply strain the water without destroying the organic 
matter. ISTo filter is germ proof. 

It is a popular error that water, no matter how im- 
pure, is made pure by passing through the soil. The 
action of the soil in this respect is very limited. The 
soil readily becomes saturated with impurities, and then 
water passing through it is rendered more impure in- 
stead of being improved. It is also erroneous to sup- 
pose that running water purifies itself so quickly that it 
may be safely used when at the same time receiving filth 
from drains or sewers. Such impurities have been traced 
in running streams for many miles. 

68. Care of Filters. — The filtering substance must 
be renewed occasionally, and the filter should be allowed 
to become empty every day or two so as to renew its 
supply of oxygen from the air, upon which its power to 
destroy organic matter depends. Foul-smelling water 
and very hard water should never be put into a filter. 
Hard water, in which the hardness is due to the pres- 
ence of lime, may be softened by boiling. 

69. The Best Water. — The purest water is undoubt- 
edly the best. Water, to be wholesome, must be free 
from organic impurities, and should contain but a small 



DRINKS. 39 

amount of inorganic salts. In Limestone regions, where 

all well and spring water is hard, cistern-water is the 
best to be obtained. An abundant supply of rain-water 
may be secured if none is wasted, as the roof of an ordi- 
nary house will collect a sufficient amount to supply a 
single family. Cistern-water should always be filtered, 
and when a perceptible odor is present, should be boiled 
before filtering. 

70. Wells. — In most country districts the water sup- 
ply for domestic purposes is furnished by wells. The wa- 
ter of shallow wells is generally softer, but more liable to 
contamination with organic impurities, than that of deep 
wells. The best wells are those made by sinking an iron 
pipe into the ground until it penetrates for some dis- 
tance, or passes through, a stratum of rock or imper- 
vious clay. What is known as the " second water " is 
thus reached, which, besides being reasonably secure 
against danger of contamination, affords a more plen- 
tiful and constant supply than that obtained from dug 
wells. 

71. Water as a Beverage. — Other beverages than 
water are useful as drinks just in proportion to the amount 
of w^ater and the harmlessness of the other substances 
which they contain. The amount of water required 
daily in food and drink is from three to five pints. 
The amount which must be taken as a drink depends 
upon the character of the food. If fluid food, such as 
soup and milk, is largely used, together with juicy fruits, 
nearly or quite the whole amount of fluid necessary may 
be taken in the food. It is often better to take water 
quite warm. Very cold or iced water should never be 
taken at meals, nor when the body is heated, nor in 
large quantities at any time. 



40 SECOND BOOK IN PHYSIOLOGY. 

Hot water is, as a rule, preferable to cold water as a 
beverage. It quenches thirst more quickly than cold 
water, because it is more readily absorbed. Cold water 
hinders digestion, while hot water, in moderate quanti- 
ties, aids digestion. Water which has been boiled is 
free from germs. It is never prudent to drink water 
which has not been boiled, unless it is known to be from 
a pure source. 

The free use of water and juicy fruits, especially in 
the warm season of the year, is an important means of 
maintaining health, and preventing attacks of sick-head- 
ache, biliousness, and similar disorders. 

72. Unwholesome Drinks. — The danger of using 
impure water is sometimes offered as an apology for the 
use of beer and other alcoholic drinks. This is certainly 
a very poor excuse. Beer is simply a mixture of water 
with alcohol and other substances, and it not infre- 
quently happens that impure water is used in its man- 
ufacture. It thus appears that ono who seeks to avoid 
danger from impure water by using beer doubles the 
danger instead of diminishing it. The tolly of this 
method of avoiding the danger from impure w^ater is 
still more apparent when we remember the fact that 
beer is sometimes adulterated with very poisonous sub- 
stances, which are more harmful even than alcohol. 

Beer, ale, wine, and other alcoholic drinks will not take 
the place of water, since the alcohol which they intro- 
duce into the system produces a feverish condition, by 
which there is created a demand for more water than 
the system naturally requires ; thus the thirst may be 
increased rather than quenched. Mead, small-beer, and t 
similar drinks only differ from other alcoholic drinks in 
the amount of alcohol which they contain, and ai^ not 



DRINKS 41 

propci* substitutes for water. One great danger in the 
use of these beverages is the fact that they create an ap- 
petite for stronger alcoholic drinks. Alcoholic liquors 
are sometimes added to the drinks sold at soda foun- 
tains, making some care necessary in the use of these 
popular beverages. 

Tea and coffee are often used as substitutes for water, 
but are much inferior to the latter for quenching thirst. 
They are undoubtedly to some extent harmful, and when 
freely used may become a source of serious disease. The 
excuse that impure water is less dangerous if taken in 
the form of tea and coffee has some slight foundation, 
since the most dangerous impurities of water are de- 
stroyed by boiling. It is evident, however, that water 
may be boiled without the addition of tea or coffee. 

SUMMARY. 

1. Water is the only substance that will quench thirst. 

2. Uses of water: To soften the food; to convey digested food into 
the blood; to remove waste matters from the tissues; to cool the body 
by evaporation from the skin. 

3. Two kinds of impurities are found in water, inorganic and organic 
or organized, the latter the more dangerous. 

4. The most dangerous of all impurities are germs. 

5. The chief sources of germs are vaults, cesspools, and drains. 

6. Ice is impure if obtained from impure water. 

7. Pure water is tasteless, colorless, odorless. 

8. Impurities in water may be detected by proper tests. 

9. Impure water may be purified by boiling and filtering. 

10. Wells should be so made as to afford security against contami- 
nation. 

11. The abundant use of pure water in some form is conducive to 
health. 

12. Such unwholesome drinks as beer, wine, cider, tea, and coffee 
are not proper substitutes for water. 



CHAPTER VI. 
THE ORGANS OF DIGESTION. 

73. The process by which food is rendered soluble 
and capable of being absorbed into the body is called 
digestion. All animals digest ; indeed, plants as well as 
animals prepare their food for use by a digestive process 
which is carried on in their leaves. 

74. The Alimentary Canal. — The process of diges- 
tion is chiefly performed in a long tortuous tube called 
the alimentary canal, which is from twenty-five to thirty 
feet in length, and reaches from the mouth to the lower 
part of the trunk. 

75. The Digestive Organs consist of this canal and 
other organs arranged along and closely connected 
with it, including various glands. The latter produce 
peculiar fluids, b}^ which the food is changed in several 
very remarkable ways, as we shall learn presently. The 
several organs which take part in the process of diges- 
tion may be named as follows : Mouth, tongue, teeth, sal- 
ivary glands, oesophagus, stomach, small intestines, colon, 
liver, and pancreas. (The relative position of the liver, 
stomach, and intestines is well shown in the cut on 
page 47.) 

76. The Mouth. — The cavity of the mouth is the ex- 
panded upper portion of the alimentarjr canal. It con- 
tains the teeth and the tongue, and receives small ducts 
or canals from the three pairs of salivary glands closely 



THE ORGANS OF DIGESTION. 



connected with it. These glands produce a fluid known 
as saliva. At the back part of the mouth arc found, 
one on each side of the tonsils, glands which help to 
form the saliva. 
The saliva con- 
tains an active 
principle, ptyar 
lin. 

77. The Teeth. 
— A tooth pre- 
sents three parts 
for examination; 
The portion 
which is seen 
above the gum, 
called the crown : 
the port ion which 
is embedded in 
the jaw, the root; 
and the narrowed 
portion which 
joins these two 
parts, called the 

neck. The interior of the tooth is filled with a fleshy 
substance, thejmlp, containing the blood-vessels and the 
nerves, which nourish the tooth and give it sensibility. 
The body of the tooth is made up of a tissue resembling 
bone. The portion which projects from the gum is cov- 
ered by a very hard, smooth substance, called enamel, 
which is so brittle as to be easily broken by violent con- 
tact with hard substances. 

78. Temporary Teeth. — The teeth which appear 
in infancy and early childhood are called temporary or 




-The Salivary Glands. 



u 



SECOND BOOK IN PHYSIOLOGY. 



milk teeth. These teeth usually make their appearance 
between the ages of seven months and two years. They 
are twenty in number, and consist, in each jaw, of four 
front teeth, or incisors, two cuspids, one on each side of 
the incisors, and four molars, or double teeth, two on 
each side. 

79. Permanent Teeth. — At the age of six to seven 
years the temporary teeth begin to give place to the 




5 L 3 2 l 

Fig. 9. — The Temporary or Milk Teeth. 
The rudiments of the Permanent Teeth are shown at 1, 2, 3, 4, 5, 6, 7, and 8. 

permanent set, which, when complete, at the age of sev- 
enteen to twenty, numbers thirty-two, each jaw contain- 
ing, in addition to those of the temporary set, four small 
double teeth, or bicuspids, and two additional molars, 



THE ORGANS OF DIGESTION. 



45 



the so-called wisdom teeth. The last of the temporary 
teeth should give place to the permanent ones not later 
than the twelfth year. 

80. The (Esophagus. — In the act of swallowing 
the food passes from the mouth downward through a 
narrow passage about nine inches in length, commonly 
called the oesophagus, or meat-pipe. The walls of this 
canal are made up in part of muscles, by the aid of 
which the food is carried through it. When empty, its 
sides lie in contact with each other. At its lower end 
a circular muscle guards the opening into the stomach. 




Fig. 10. — The Stomach. 

81. The Stomach. — This is a dilated portion of the 
alimentary canal, somewhat pear-shaped in form, and ca- 
pable of holding from one to tw^o quarts. The walls of 
the stomach, like those of the entire digestive canal, are 
made up largely of thin layers of muscle, by means of 
which it is able to change its size and shape, and so to 
act upon the food as to produce a sort of churning action. 

82. The Peptic Glands. — The lining membrane of 
the stomach, when examined with a microscope, is found 



46 SECOND BOOK IN PHYSIOLOGY. 

to present multitudes of minute openings, each of which 
is found, on further examination, to communicate with 
a narrow tube which is embedded in the walls of the 
stomach. This little pocket is lined with minute living 
cells, which, during the digestion of a meal, are engaged 
in making an important digestive fluid, the gastric juice. 
The gastric juice is intensely acid. It contains two di- 
gestive principles, pepsin and rennin. 

S3. The Pylorus. — Each end of the stomach is 
guarded by a circular muscle. That at the lower or 
right end is known as the pylorus. By means of these 
muscles, the openings of the stomach are kept tightly 
closed while the process of digestion is going on. 

84. The Small Intestine. —This portion of the ali- 
mentary canal is about twenty feet in length, reaching 
from the stomach to the large intestine, which it joins 
at the lower right portion of the cavity of the abdomen. 
The walls of the intestine are muscular, like those of 
the stomach. Its mucous lining contains many glands, 
which produce an alkaline digestive fluid known as in- 
testinal juice, and is covered with giant cells which de- 
fend the body against germs. During digestion, the 
muscular walls of the intestines are in constant motion. 

85. The Absorbents. — The mucous membrane of 
the small intestine presents numerous folds, and also 
contains peculiar structures for aiding ahsorption — the 
villi. The villi are hair-like projections of mucous mem- 
brane, which hang out into the cavity of the intestine. 
Each villus contains blood-vessels and lymph-channels. 

86. The Large Intestine, or Colon. — This portion 
of the alimentary canal is about five feet in length, and 
is much larger in diameter than the small intestine. It 
begins at the lower right side of the abdominal cavity, 



THE ORGANS OF DIGESTION. 



17 




where it is joined by the small intestine. From this 
point the colon passes upward to the lower border of the 
ribs, crosses over to the left side, then passes down to 
the lower left portion of the 
abdomen, and thence back- 
ward, finally terminating in 
the rectum. 

^1. The Liver. — Lying 
chiefly at the right side, just 
above the lower border of the 
ribs, and partly covering the 
stomach, is the largest gland 
in the body, the liver. At the 
under side of the liver is a sac, 
or pouch, known as the gall- 
bladder, in which is stored up a 
fluid formed by the liver ; this 
fluid is called the bile. A short 
canal, or duct, connects both 
the gall-bladder and the liver 
with the small intestine at a 
point a few inches below the 
stomach. 

88. The Bile.— Human bile 
is alkaline, somewhat viscid, 
and of a golden-brown color 
when fresh. When vomited, Fig.n. 
bile is often green or yellow, 

as the result of changes produced in the stomach by 
contact with the acid gastric juice. The bile of the ox 
is of a greenish color. 

A remarkable fact in relation to the structure of the 
liver is that it is supplied with two sets of blood-vessels. 




ml 

The Alimentary Canal. 



48 SECOND BOOK IN PHYSIOLOGY. 

The extra system of vessels brings to the liver the blood 
from the stomach, intestines, and other digestive organs, 
and constitutes the portal circulation. 

89. The Pancreas. — Just behind the stomach is a 
long curiously shaped gland, known as the pancreas, 
which secretes the pancreatic juice. This is a fluid much 
like saliva. It is produced during the digestion of a meal, 
and is poured into the small intestine through a duct 
which joins that from the liver, and with it opens into 
the intestinal canal four or five inches below the stomach. 

The pancreatic juice contains four active principles, 
amylopsin, trypsin, steapsin, and ^milk-curdling ferment. 

SUMMARY. 

1. Digestion is a process by which the various food substances are 
dissolved, and prepared for absorption into the blood. 

2. Both plants and animals digest. 

3. The digestive apparatus consists of the alimentary canal and 
various organs connected with it — the mouth, teeth, salivary giands, 
oesophagus, stomach, small intestines, colon, liver, and pancreas. 

4. There .are two sets of teeth — the temporary or milk teeth, and the 
permanent teeth. 

5. The salivary glands produce the saliva. 

6. The peptic glands of the stomach produce an acid digestive 
fluid, the gastric juice. 

7. The intestinal glands produce the intestinal juice. 

8. The liver produces an alkaline fluid, the bile. 

9. The liver has two sets of blood-vessels. The extra set collects 
blood from the veins of the stomach, intestines, pancreas, and spleen, 
which together form the portal circulation. 

10. The pancreas produces the pancreatic juice. 

11. There are five digestive fluids — the saliva, the gastric juice, the 
bile, the pancreatic fluid, the intestinal juice. 



CHAPTER VII. 
THE DIGESTIVE FLUIDS. 

90. The Digestive Fluids. — In studying the or- 
gans of digestion, we learned that there are five digest- 
ive fluids, viz. : the saliva, the gastric juice, the bile, the 
pancreatic juice, and the intestinal juice. In the pre- 
ceding chapter we have learned that there are five 
digestible food elements, viz. : starch, albumen,* fats, 
sugars, and salts. Let us now study carefully the use 
of each digestive fluid in relation to the various food 
elements. 

Much of the information which has been gained re- 
specting the action of the stomach upon the food is due 
to the persevering and accurate observations of Dr. 
Beaumont, a surgeon in the American army, who, in 
1822, while stationed in what was then known as " Mich- 
igan Territory," was called upon to take charge of the 
case of a young Canadian by the name of Alexis St. 
Martin, who had been accidentally wounded in the side 
by the discharge of a musket loaded with shot, at a dis- 
tance of one yard from his body. A portion of flesh as 
large as a man's hand was torn away from his side, leav- 
ing large openings into both the stomach and the chest. 
The opening communicating with the chest cavity finally 

* The word albumen is used to represent all the albuminous elements 
of the food — albumen, gluten, caseine, etc. 



50 SECOND BOOK IN PHYSIOLOGY. 

closed up entirely, but the opening into the stomach 
remained. Immediately after his recovery it was about 
two and one-half inches in diameter. Whatever was 
swallowed passed out through this opening, making it 
necessary to wear a pad for some time to close the open- 
ing. In time nature remedied the difficulty by growing 
over the opening, upon the inside, a loose fold of mem- 
brane which effectually closed it, but at the same time 
could be easily pushed aside, thus allowing a full view 
of the interior of the stomach. 

Great and important additions to our knowledge of 
digestion have been made recently by the use of the 
" stomach tube," a flexible rubber tube, by means of 
which digesting food may be removed from the stomach 
for chemical examination. The facts thus learned give 
us more positive and definite information respecting the 
work of the stomach and the digestive properties of 
food than we have previously possessed, and throw 
great light upon the hygiene of digestion. 

91. What the Saliva Digests. — A dry crust of 
bread, chewed for some minutes, becomes sweet. This 
is due to the fact that the saliva contains a peculiar 
principle which, when brought into contact with boiled 
starch, converts it into grape-sugar. This conversion 
into sugar constitutes the digestion of starch. It is es- 
sential, however, that the starch should be cooked, as 
the saliva cannot readily digest raw starch. Each little 
granule is surrounded by a thin shell of woody matter, 
or cellulose, which the saliva cannot dissolve. The sa- 
liva also stimulates the stomach to secrete gastric juice. 

92. What the Gastric Juice Digests. — Pepsin, 
one of the active principles of the gastric juice, acts 
upon the albuminous elements of the food, such as egg- 



THE DIGESTIVE FLUIDS. 51 

albumen, the fibrine of meat, gluten of grains, caseine of 

milk, etc. By its action all of these various substances 
are converted into one simple substance, known as pep- 
tone, which is readily absorbed into the blood, while un- 
digested albumen cannot be absorbed to any great ex- 
tent, and, if absorbed, would be of no use in the system. 
The gastric juice prepares the food for further digestion 
by dissolving the substances by which the various ele- 
ments of the food are held together. Eennin curdles 
milk. 

Carbolic acid, common salt, and numerous other sub- 
stances are called antiseptics, because they prevent fer- 
mentation or decay. The gastric juice and the bile pos- 
sess this remarkable property. A dog w 7 as fed with 
putrid meat. On being killed, an hour after, the meat, 
which had been extremely offensive, w r as apparently 
perfectly fresh. This property of the gastric juice is ex- 
ceedingly important, as it prevents decay or fermenta- 
tion in the stomach before digestion can take place. 

93. What the Bile Digests. — Like the saliva and 
the gastric juice, the bile digests but a single one of the 
digestible food elements. Its action is wholly upon the 
fatty portions of the food. If oil and water are shaken 
together in a bottle, they quickly separate when the 
shaking ceases. Gum-water and oil, when shaken to- 
gether, form a milky mixture in which the oil and the 
water do not separate, and which may be diluted with 
water the same as milk. The bile acts upon fats in the 
same manner. Such a mixture is called an emulsion. 
Under a microscope, the oil of an emulsion is seen to be 
divided up into very fine drops or globules. 

94. What the Pancreatic Juice Digests. — The 
pancreatic juice digests each of the three principal food 



52 SECOND BOOK IN PHYSIOLOGY. 

elements — starch, albumen, and fats. Amylopsin con- 
verts starch into sugar, trypsin changes albumen into 
peptone, and steapsin makes an emulsion of the fats. 
The pancreatic juice does the work of all three of the 
preceding digestive fluids — the saliva, the gastric juice, 
and the bile. 

95. What the Intestinal Juice Digests. — This 
fluid possesses but one characteristic digestive property. 
Cane-sugar is ordinarily digested only in the small in- 
testine, and by the action of the intestinal juice. The 
intestinal juice also digests starch, albumen, and fats, 
and, together with each of the other digestive fluids, 
acts upon the salts of the food. 

In herbivorous animals, and to a small extent in man, 
cellulose is digested in the large intestine. 

SUMMARY. 

1. There are five digestive fluids — saliva, gastric juice, bile, pancre- 
atic juice, intestinal juice. 

2. There are five digestible food elements — starcb, albumen, fats, 
sugar, salts. 

3. The saliva digests starch. 

4. The gastric juice digests albumen. 

5. The bile digests fats. 

6. The pancreatic juice digests starch, albumen, and /to. 

7. The intestinal juice digests starch, albumen, fats, and cane-sugar. 
B. All the digestive fluids digest the salts. 

9. Starch is digested by the saliva, pancreatic juice, and intestinal 
juice. 

10. xALbumen is digested by the gastric juice, pancreatic juice, and 
intestinal juice. 

11. Fats are digested by the bile, pancreatic juice, and intestinal juice. 

12. Cane-sugar is digested by the intestinal juice alone. 

13. The salts are digested by all the digestive fluids. 

14. The digestive process changes starch and cane-sugar to grape- 
sugar, albumen to peptone, fats to emulsion, and dissolves the salts. 



CHAPTER VIII. 
GENERAL VIEW OF THE DIGESTIVE PROCESS. 

96. The digestive process begins the moment a mor- 
sel of food enters the mouth, and continues throughout 
the entire length of the alimentary canal, or until the 
digestible portions of the food have been completely 
digested. 

97. Mastication. — The first act in the digestive 
process is mastication, or chewing the food, the purpose 
of which is to crush the food and divide it into small 
particles, so that the various digestive fluids may easily 
and promptly come into contact with every part of it. 

98. Salivary Digestion. — The saliva softens the 
food, and thus prepares it for the action of the other 
digestive fluids. It also acts upon the starch, convert- 
ing a portion of it into sugar. 

99. Deglutition, or Swallowing. — In the act of 
swallowing, the food does not drop down through an 
open tube, but is seized by the muscles at the back of 
the mouth, and is carried down into the stomach by the 
oesophagus. 

100. Stomach Digestion. — After receiving the food, 
the stomach soon begins to pour out the gastric juice, 
which first makes its appearance in little drops, like 
beads of sweat upon the face when the perspiration 
starts. As the quantity increases, the drops run togeth- 
er, trickle down the sides of the stomach, and mingle 



54 SECOND BOOK IN PHYSIOLOGY. 

with the food. The muscular walls of the stomach con- 
tract upon the food, moving it about with a sort of 
churning action, thoroughly mixing the gastric juice 
with the food. During this process both the openings 
of the stomach are tightly closed. The gastric juice 
softens the food, digests albumen, and coagulates milk. 
The saliva continues its action upon starch for some 
time after the food reaches the stomach. 

101. Action of the Pylorus.— After the food has re- 
mained in the stomach from one to three hours, or 
even longer, if the digestion is slow or indigestible foods 
have been eaten, the contractions of the stomach become 
so vigorous that the more fluid portions of the food are 
squeezed out through the pylorus, thus escaping into the 
intestine. The pylorus does not exercise a species of in- 
telligence in the selection of the food, as was once sup- 
posed. The increasing acidity of the contents of the stom- 
ach causes its muscular walls to contract with increasing 
vigor, until finally those portions of the food which may 
be less perfectly broken up, but which the stomach has 
been unable to digest, are forced through the pylorus. 

102. Intestinal Digestion. — As it leaves the stom- 
ach, the partially digested mass of food is intensely 
acid, from the large quantity of gastric juice which it 
contains. Intestinal digestion cannot begin until the 
food becomes alkaline. The alkaline bile neutralizes the 
gastric juice, and renders the digesting mass slightly 
alkaline. The bile also acts upon the fats of the food, 
converting them into an emulsion. The pancreatic juice 
converts the starch into sugar, digesting both raw and 
cooked starch. It also digests fats and albumen. The 
intestinal juice continues the work begun by the other 
digestive fluids, and digests cane-sugar. 



GENERAL VIEW OF THE DIGESTIVE PROCESS. 55 

103. Other Uses of the Digestive Fluids. — In 
addition to the uses of which we have already learned, 
several of the digestive fluids possess other interesting 
properties. The saliva aids the stomach, by stimulating 
its glands to make gastric juice. The gastric juice and 
the bile are excellent antiseptics, by which the food is 
preserved from fermentation while undergoing diges- 
tion. The bile also stimulates the movements of the in- 
testines by which the food is moved along, and aids ab- 
sorption. It is a remarkable and interesting fact that a 
fluid so useful as the bile should be at the same time 
largely composed of waste matters which are being re- 
moved from the body. This is an illustration of the 
wonderful economy shown by Nature in her operations. 

104. Peristaltic Action. — The food is moved along 
the alimentary canal, from the stomach downward, by 
successive contractions of the muscular walls of the in- 
testines, known as peristaltic movements, which occur 
with great regularity during digestion. 

105. Absorption. — The absorption of the food begins 
as soon as any portion has been digested. Even in the 
mouth and the oesophagus a small amount is absorbed. 
The entire mucous membrane lining the digestive canal 
is furnished with a rich supply of blood-vessels, by 
which the greater part of the digested food is absorbed. 
Absorption is greatly aided by a rhythmical contraction 
of the villi, which is in effect a sort of pumping action, 
alternately filling and emptying the lacteal and venous 
absorbents. The action of the diaphragm in normal 
breathing also aids absorption by emptying the blood- 
vessels of the stomach and intestines. During absorp- 
tion, the digested food is changed into blood. 

106. The Lacteals. — The walls of the intestines con- 



56 SECOND BOOK IN PHYSIOLOGY. 

tain certain small vessels called lacteals, on account of 
their white appearance after a meal. This appearance 
is due to the digested fat which they contain, and which 
it is their special duty to absorb. The small lacteal ves- 
sels unite to form larger ones, all joining at last in one 
large one about the size of a crow's quill, called the 
thoracic duct, which passes upward and connects with 
the large veins that return the blood from the left arm. 

107. The Portal Vein. — The veins of the stomach, 
intestines, pancreas, and spleen all unite to form one 
large vein, called the portal vein. Instead of emptying, 
as do other veins, into the large vein which goes to the 
heart, the portal vein conveys its blood to the liver, 
through which it is distributed by a special set of ves- 
sels. Afterwards it is gathered up by another large 
vein, and carried to the heart. Thus it appears that all 
of the food absorbed by the blood-vessels of the stomach 
and intestines, constituting the greater part of what is 
digested, is carried to the liver before entering the gen- 
eral circulation. 

108. Liver Digestion. — The liver not only secretes 
a digestive fluid, the bile, but it acts upon the food 
brought to it by the portal vein, and regulates the sup- 
ply of digested food to the general system. It converts 
a large share of the grape-sugar and partially digested 
starch brought to it into liver-starch, commonly termed 
glycogen, which it stores up in its tissues. During the 
interval between the meals, the liver gradually redigests 
the glycogen, reconverting it into sugar, and thus sup- 
plying it to the blood in small quantities, instead of al- 
lowing the entire amount formed in digestion to enter 
the circulation at once. If too large an amount of 
sugar entered the blood at once, the system would be 



GENERAL VIEW OF THE DIGESTIVE PROCESS. :>7 

tumble to use it all, and would be compelled to get rid 
of a considerable portion through the kidneys. 

The remarkable function by which the liver stores 
up starch within its tissues is usefully employed as a 
means of protecting the body from various poisons. 
AVhen arsenic, mercury, lead, or any other metallic poi- 
son is taken into the stomach, any portion absorbed is 
carried to the liver, which absorbs and retains as much 
as possible of the poison, and thus protects the rest oi: 
the body. The liver treats alcohol and other narcotics 
in the same manner; and it is doubtless for this reason 
that the liver suffers so great damage from the use of 
alcoholic drinks, tobacco, and other narcotic substances. 
Vegetable poisons and undigested food substances are 
also destroyed by the liver. 

SUMMARY. 

1. There are five general divisions of the digestive apparatus — 
mouth, stomach, liver, pancreas, intestines. 

2. Corresponding to these there are five digestible food elements, 
which are digested by five digestive fluids. 

3. There are ten digestive processes — mastication, salivary diges- 
tion, deglutition, gastric digestion, biliary digestion, pancreatic diges- 
tion, intestinal digestion, peristaltic action, absorption, liver digestion. 

4. Besides digesting starch, the saliva softens the food and stimu- 
lates the secretion of gastric juice. 

5. Besides digesting albumen, the gastric juice preserves the food 
from fermentation. 

6. Besides digesting fats, the bile prevents decay of the food in the 
bowels, aids absorption, and stimulates peristaltic action. 

7. The lacteals absorb the digested fat. 

8. The veins of the stomach, spleen, pancreas, and intestines unite to 
form the portal vein. 

3* 



CHAPTER IX. 
THE HYGIENE OF DIGESTION. 

109. The hygiene of digestion has to do with the 
quality and quantity of food eaten, and the manner* of 
eating it. 

110. Hasty Eating. — If the food is eaten too rapid- 
ly, it will not be properly divided, and when swallowed 
in coarse lumps, the digestive fluids cannot readily act 
upon it. On account of the insufficient mastication, 
the saliva will be deficient in quantity, and, as a con- 
sequence, the starch will not be well digested, and the 
stomach will not secrete a sufficient amount of gastric 
juice. It is not well to eat only soft or liquid food, as we 
are likely. to swallow it without proper chewing. Cows 
fed upon " slops " soon lose their teeth, and become oth- 
erwise unhealthy. A considerable proportion of hard 
food, which requires thorough mastication, should be 
eaten at every meal. 

111. Drinking Freely at Meals is harmful, as it 
not only encourages hasty eating, but dilutes the gastric 
juice, and thus lessens its activity. The food should be 
chewed until sufficiently moistened by the saliva to allow 
it to be swallowed. "When large quantities of fluid are 
taken into the stomach, digestion does not begin until 
a considerable portion of the fluid has been absorbed. 
If cold foods or drinks are taken with the meal, such 
as ice-cream, ice- water, iced milk or tea, the stomach is 



THE HYGIENE OF DIGESTION. b\) 

chilled, and a long delay in the digestive process is occa- 
sioned. Dr. Beaumont noted this fact in his observa- 
tions upon the process of digestion in St. Martin. 

The Indians of Brazil carefully abstain from drinking 
when eating, and the same custom prevails among many 
other savage tribes. 

112. Eating between Meals. — The habit of eating 
apples, nuts, fruits, confectionery, etc., between meals is 
exceedingly harmful, and certain to produce loss of ap- 
petite and indigestion. The stomach, as well as the 
muscles and other organs of the body, requires rest. The 
frequency with which meals should be taken depends 
somewhat upon the age and occupation of an individ- 
ual. Infants take their food at short intervals, and, 
owing to its simple character, are able to digest it very 
quickly. Adults should not take food more frequently 
than three times a day; and persons whose employ- 
ments are sedentary may, in many cases at least, adopt 
with advantage the plan of the ancient Greeks, who ate 
but twice -a day. The latter custom is quite general 
among the higher classes in France and Spain, and is 
gaining ground in this country. 

113. Simplicity in Diet. — Taking too many kinds 
of food at a meal is a common fault in well-to-do fami- 
lies, and is a cause of disease of the digestive organs. 
Those nations are the most hardy and enduring whose 
dietary is the most simple. The Scotch peasantry live 
chiefly upon oatmeal, the Irish upon potatoes, milk, and 
oatmeal, the Italian upon peas, beans, macaroni, and 
chestnuts ; yet all these are noted for remarkable health 
and endurance. The natives of the Canary Islands, an 
exceedingly well - developed and vigorous race, subsist 
almost exclusively upon a food which they call gojio. 



60 SECOND BOOK IN PHYSIOLOGY. 

consisting of parched grain coarsely ground in a mortar 
and mixed with water. 

The stomach cannot well digest a mixture of many 
different kinds of food at the same meal, though it 
might digest well any one or two of them if taken 
alone. The practice of supplementing a hearty dinner 
by a dessert of rich puddings and sauces is unwhole- 
some, as it not only adds to the more than ample varie- 
ty of articles already eaten, but leads to overeating. 

114. Eating when Tired. — It is not well to eat 
when exhausted by violent exercise, as the system is not 
prepared to do the work of digestion well. Sleeping im- 
mediately after eating is also a harmful practice. The 
process of digestion cannot well be performed during 
sleep, and sleep is disturbed by the ineffective efforts of 
the digestive organs. Hence the well-known evil effects 
of late suppers. 

115. Eating Too Much. — Hasty eating is the great- 
est cause of overeating. When one eats too rapidly, the 
food is crowded into the stomach so fast that nature 
has not time to cry " enough," by taking away the ap- 
petite before too much has been eaten. When excess 
of food is taken, the food is likely to ferment or sour 
before it can be digested. One who eats too much usu- 
ally feels dull after eating. 

116. How Much Food is Enough? — The proper 
quantity for each person to take is what he is able to 
digest and utilize. This amount varies with each indi- 
vidual, and for the same individual, at different times. 
The amount needed will vary with the amount of work 
done — mental or muscular ; with the weather or season 
of the year — more food being required in cold than in 
warm weather ; with the age of an individual — very old 



THE BYGIENE OF DIGESTION. 



61 



and very young persons requiring less food than those of 
middle-age. An unperverted appetite, not artificially 
stimulated, is a safe guide. Drowsiness, dulness, and 
heaviness at the stomach are indications of excess in 
eating, and naturally suggest a lessening of the quantity 
of food, unless the symptoms are known to arise from 
some other cause. 

117. Cookery. — Proper cooking of food is a sort of 
artificial digestion. Each of the food elements, with the 
exception of fats, is improved by cooking, being changed 
by the action of heat in much the same way as by the 
action of the digestive fluids. Fats, on the contrary, 
are rendered less digestible, especially when exposed to 
heat for any considerable length of time, or to a high 
degree of heat even for a brief period, as in frying. 

US. Bread-making. — From the earliest ages, bread 
in some form has 
constituted an im- 
portant element 
in the bill of fare 
of all nations ac- 
quainted with the 
art of bread-mak- 
ing. There are 
essentially three 
kinds of bread — 
leavened bread, 
unleavened bread, 
and bread raised 
from some form 
of baking-pow- 
der. Leavened bread is made by adding yeast to a 
mixture of flour and water, and allowing it to " rise," 




Fig. 12. — A Grain of Wheat. 
Outer Envelope, b. Gluten Layer, c. Starch Cells. 



62 SECOND BOOK IN PHYSIOLOGY. 

or ferment, a process in which a portion of the constit- 
uents of the grain is decomposed into alcohol and car- 
bonic acid gas. The gas bubbles up through the dough, 
and being retained by the tenacious gluten, makes the 
bread light. 

Unleavened bread is made by working into the dough 
a considerable quantity of air, which expands by the 
action of the heat, while a portion of the moisture of 
the loaf is converted into steam. The steam and heated 
air, in rising through the loaf, form bubbles which make 
it light. 

Baking-powders consist of chemical substances which 
generate carbonic acid gas when moistened. By mixing 
thein with the flour, the bread is made light in essen- 
tially the same way as when fermented. 

Unleavened bread, when well made, is by far the most 
healthful of the three kinds, though the art of making 
it, which was well known among the ancients, and is still 
practised by many barbarous tribes, seems to have been 
nearly lost by civilized nations. The hoe-cake of the 
South and the beaten bread of Virginia are excellent 
specimens of unleavened bread. 

119. Bad Cookery. — While good cookery is an im- 
portant aid to digestion, bad cookery is as great a hinder- 
ance, and is a cause of disease. Frying and other meth- 
ods of cooking with fats are especially objectionable, As 
fat is not acted upon either by the saliva or by the gas- 
tric juice, a morsel of food which is saturated with fat re- 
mains undigested in the stomach, and does not begin to 
be digested until it reaches the small intestines, and comes 
in contact with the pancreatic juice and the bile. 

The use of pastry, rich cake, hot buttered toast, and 
similar articles, is objectionable on the same ground. 



THE HYGIENE OF DIGESTION. 63 

Hashes, stews, and sausages are usually greasy messes 
wholly unfit to be eaten. In mince-pies, besides un- 
wholesome condiments and various indigestible ingre- 
dients, there is usually more or less alcohol, which ren- 
ders them doubly objectionable. Imperfectly cooked 
or raw food, when habitually used, causes indigestion. 

L20. Excess of Certain Food Elements. — When 
sugar is too freelv used, either with food or in the form of 
sweetmeats or candies, indigestion, and even more seri- 
ous disease, is likely to result. We should remember 
that the starch, which constitutes so large a part of our 
food, is all converted into sugar in the process of diges- 
tion, so that a very small amount of sugar will suffice 
to meet the demands of the system. Fats, when freely 
used, give rise to indigestion and " biliousness." An ex- 
cess of albumen from the too free use of meat is harm- 
ful. Only a limited amount of this element can be 
used ; any excess is treated as waste matter, and must 
be removed from the system by the liver and the kid- 
neys. Most persons would enjoy better health by using 
meat less freely than is usual in this country, and per- 
fect health can be maintained without flesh-food. 

121. Deficiency of Certain Food Elements. — A 
diet deficient in any important food element is even more 
detrimental to health than a diet in which certain ele- 
ments are in excess. Superfine white flour consists chief- 
ly of the starchy central portion of the grain, the outer 
layers, which are rich in albuminous elements, having 
been removed with the bran. The most wholesome flour 
is wheat meal or Graham flour, or a still more perfect 
preparation known as "whole-wheat'' or " entire- w^heat " 
flour, which contains all the nutritive elements of the 
grain. 



64 SECOND BOOK IN PHYSIOLOGY. 

The popular notion that beef-tea and meat extracts 
contain the nourishing elements of meat in a concen- 
trated form, is a dangerous error. Undoubtedly, many 
sick persons have been starved by being fed exclusively 
upon these articles, which are almost wholly composed 
of waste substances. Professor Claude Bernard, of Paris, 
found that dogs fed upon meat extract died sooner than 
those which received only water. 

122. Unripe and Decayed Foods. — Immature 
fruits — as unripe apples, pears, peaches, etc. — are ex- 
ceedingly difficult to digest, and likely to cause serious 
disease. On the other hand, foods which are over-ripe, 
or which have begun to decay, are equally objectionable. 
Animal food with a " high flavor," which is evidence that 
decomposition has begun, is especially dangerous. Game 
sent to market without being " drawn," should never 
be eaten. Cases of poisoning are frequently traced to 
the use of canned meat which has decomposed as the 
result of imperfect canning, or after the can has been 
opened. Fish and oysters are especially liable to this 
kind* of decomposition. 

Cheese sometimes undergoes a kind of fermentation 
which renders it extremely poisonous. Such cheese, 
when tested with blue " litmus-paper," proves to be acid 
by turning the paper red. Cheese also frequently con- 
tains the young of a fly, familiarly known as " hoppers" 
or "skippers." The cheese-mite is another parasite of 
cheese. Cheese is difficult to digest, and hence is a fre- 
quent cause of severe illness. Yery old cheese is wholly 
unfit for food. 

Sour or stale milk, mouldy bread, or other stale or 
sour foods, should never be eaten. Boiling milk will de- 
stroy any germs which it may contain. During the hot 



THE HYGIENE OF DIGESTION. 



65 



months the milk fed to young children should always 
bo hoi led. A large share of the sickness from which 
infants suffer may be prevented by this simple means. 

123. Diseased Foods. — All domestic animals that 
are used as food are subject to diseases which render 
their flesh liable to cause sickness if eaten. The proc- 
ess of fattening is frequently productive of disease. 
Animals are often kept under conditions most unfavor- 
able to health, and thereby become diseased. 

The hog is sometimes infested by a parasite called 
trichina. These parasites, when taken into the stomach 
by eating pork, 
rapidly increase in 
numbers, and the 
young trichinae 
soon find their 
way to all parts 
of the body. Vio- 
lent illness, and 
even death, is of- 
ten caused in this 
way. One cannot 
eat uncooked or 
imperfectly cook- 
ed pork without 
running the risk 
of infection by 
these parasites, which, when once received into the sys- 
tem, are retained during an individual's life. Pork is 
much less wholesome than most other kinds of flesh, 
and is more difficult to digest. 

Meat should always be carefully inspected before it 
is purchased. If it lias a very dark red color, the ani- 




Fig. 13. — Trichina in Pork. 



66 SECOND BOOK IN PHYSIOLOGY. 

mal, when killed, was probably suffering with some sort 
of fever. A very pale or yellow color in meat indicates 
an unhealthy condition of the animal — as consumption, 
scrofula, or jaundice. Small white specks in the flesh 
indicate the presence of trichinae, and larger white 
specks the embryos of the tape-worm. When a knife is 
drawn through the flesh, if the juice of the meat adheres 
to it, it should be rejected. Meat which has the slight- 
est taint or odor of decomposition should not be eaten. 

The milk of diseased cows is unwholesome, and the 
same must be said of the milk of cows that are kept in 
close, unventilated stalls, and do not receive healthful 
food and proper care. It is quite possible that con- 
sumption, which is increasingly prevalent among cows, 
may be communicated to human beings through the 
use of the milk of consumptive cows. Milk should on 
this account invariably be boiled unless known to be 
from a healthy animal. 

Ergot in wheat and rye, rust in various grains, and 
the "yellows" in peaches, are examples of disease in 
vegetable foods which renders them unfit for use. 

124. Adulteration of Foods. — The adulteration of 
foods is practised to a very great extent, especially in 
large cities. Milk is most likely to be adulterated with 
water, though sometimes various mixtures are added. 

In recent years, sugar has become to an enormous ex- 
tent the subject of adulteration with glucose, the artifi- 
cial sugar made from corn. Yery few of the syrups now 
sold are free from this adulterant, and the cheap sugars 
are about equally open to suspicion. Honey and maple 
syrup are often largely adulterated with glucose. 

Many of the fruit flavors and jellies sold in the stores 
are either wholly artificial or very largely adulterated. 



THE HYGIENE OF DIGESTION. 07 

Tea and coffee are often adulterated. Ground coffee usu- 
ally contains almost anything but real coffee, of which 
it often contains not a particle. Vinegar is frequently 
adulterated with oil of vitriol and other mineral acids. 

125. Indigestible Foods. — Such indigestible foods 
as preserves, pickles, ices, etc., are productive of much 
mischief to the digestive organs, and will be avoided by 
those who value a good digestion. 

120. Condiments. — Such irritating and stimulating 
substances as mustard, pepper, pepper-sauce, and other 
condiments are in no sense foods. They act upon the 
digestive organs as whips to goad them to the perform- 
ance of more work than ought to be required of them, 
and more than they are really able to do. The ultimate 
result is debility and disease. Condiments also encour- 
age overeating. 

Salt is about the only condiment allowable, and this 
is generally used too freely. Many wild tribes, and 
most animals, enjoy excellent health without adding 
salt to their natural food. Vinegar is of doubtful value. 
It often contains minute creatures known as vinegar eels. 
Lemon-juice or lime-juice is a good substitute. Pickles 
are wholly unfit for food. 

127. Substances not Foods. —Soda, scderatus, cream 
of tartar, and the various baking-powders so commonly 
used in cookery are all more or less objectionable. Bak- 
ing-powders often contain cdum, which renders them 
still more harmful. The habit of eating clay, charcoal, 
plaster, chalk, etc., which is sometimes acquired, is very 
detrimental to health, and may cause fatal illness. 

128. Hygiene of the Bowels. —The "call of nat- 
ure" to relieve the bowels should receive prompt at- 
tention, and, if possible, at a regular hour each day. 



68 SECOND BOOK IN PHYSIOLOGY. 

Numerous diseases, some of a very serious character, 
grow out of the neglect of this duty. 

129. Hygiene of the Teeth. — First of all, see that 
they are thoroughly cleansed after each meal by rins- 
ing with water and by the use of a wooden toothpick. 
Every particle of food must be carefully removed from 
between the teeth. If allowed to remain, the food 
decomposes, and causes decay of the teeth. The teeth 
should also be cleansed each night and morning by means 
of a soft brush and plenty of water. A little precipi- 
tated- chalk may be used two or three times a week. 
Cracking nuts or biting hard substances with the teeth 
may cause serious mischief, by breaking the tooth or in- 
juring the enamel. Pain in a tooth is an indication of 
disease, and if it is constant^ or recurs frequently, a com- 
petent dentist should be consulted. The first beginning 
of decay should receive prompt attention. A small cav- 
ity, if not filled at once, may in a short time become so 
large as to destroy the tooth. Never sacrifice a tooth 
if it can be saved. 

SUMMARY. 

1. The chief errors respecting diet are in relation to the quantity 
and quality of food, and the manner of eating. 

2. We may err in the manner of eating by eating hastily, drink- 
ing freely at meals, taking very cold or iced foods or drinks at meals, 
eating between meals, or too frequently, lack of simplicity in diet, 
eating when exhausted, or shortly before retiring. 

3. We may err as regards the quantity of food by taking either too 
much or too little. 

4. Food, to be of good quality, must be properly cooked; condi- 
ments and chemicals are unwholesome, fried or greasy food is veiy 
indigestible ; food elements must be in right proportion; food must be 
mature, but not decayed. 

5. The bowels must receive regular and prompt attention. 

6. The teeth must be properly used, carefully cleansed daity, and 
rilled as soon as decay begins. 



CHAPTER X. 

ALCOHOLIC DRINKS, TOBACCO, AND OTHER NAR- 
COTICS. 

130. Narcotics are drugs which have a stupefying 
effect upon the brain and the nerves. In small doses, 
many narcotics produce an appearance of increased 
strength and activity. Some of these drugs on this ac- 
count have been called stimulants. It may be here 
stated, however, that a stimulant does not increase 
strength, but rather diminishes strength, as we shall 
learn in a future chapter. All narcotics, and the so- 
called stimulants, if taken in sufficient doses, cause in- 
sensibility and death. The most injurious articles of 
this class in common use are alcohol, tobacco, opium, tea, 
and coffee. A new drug, even more dangerous than any 
of the above, has recently come into use. It is known 
as cocaine. It is made from the leaves of the coca-tree, 
which are used for a beverage in South America, as tea 
leaves are used in this and other countries. These sub- 
stances have been aptly called "vice-drugs." 

131. What is Alcohol? — Alcohol is a chemical 
substance which has been used in some form from the 
most ancient times, although known in a pure state for 
but a few hundred years. As a chemical compound, 
alcohol is closely related to naphtha and a number of 
similar substances. 

132. How Alcohol is Produced. — Unlike grains, 
fruits, and other food substances, alcohol does not grow. 



70 SECOND BOOK IN PHYSIOLOGY. 

It is not produced by any plant, tree, or shrub. It is 
rather the result of death — of a process of decay or 
fermentation, the nature of which we may study with 
interest and profit. 

133. Fermentation. — The process of fermentation 
is the result of the action of a microscopic plant famil- 
iarly known as yeast. This curious plant, and the proc- 
ess of fermentation set up by it, serve a useful purpose 
in the familiar household operation of bread - making. 
Yeast spores and other germs are constantly present in 
the air. Atmospheric dust is made up in part of these 
minute living forms. When these germs come in con- 
tact with animal or vegetable substances, under proper 
conditions as regards warmth and moisture, various 
changes are produced, the result of which is decomposi- 
tion or decay. The various forms of mould and mildew 
are produced by germs. The decay of fruits and vege- 
tables, and the putrefaction of flesh, are due to different 
species of germs, which produce these particular kinds 
of decay. Several species of germs are capable of pro- 
ducing the destructive change which we call fermenta- 
tion. When these germs come into contact with a wa- 
tery solution containing sugar, fermentation is set up, 
and the sugar is decomposed into alcohol and carbonic 
acid gas. The alcohol remains in the solution, while the 
carbonic acid gas bubbles up through the solution and 
escapes. If the fermentation continues long enough, the 
alcohol is decomposed into acetic acid and water, which 
is commonly known as vinegar. (See Experiment 3, 
page 271.) 

It is not necessary to add yeast to a fermentable 
liquid to produce fermentation, as by simple exposure 
to the air a sufficient number of germs will be deposited 



STIMULANTS AND NARCOTICS. 71 

in the liquid to begin the process, and the germs will 
multiply so rapidly that although they may not be many 

at first, a few hours will suffice to produce them in 
countless numbers. 

The juices of sweet fruits and vegetables, and decoc- 
tions made by steeping grains or starchy vegetables in 
water, undergo fermentation with great readiness. Any 
solution containing animal or vegetable matter, with sug- 
ar, will readily ferment, unless some substance is added 
to destroy the germs or prevent their activity. 

13i. Bread-making.— The ordinary process of bread- 
making is an excellent illustration of the process of fer- 
mentation. Flour stirred up with water and put into 
a warm place soon begins to " rise," or ferment. The 
germs of fermentation contained in the flour and the 
water, or received from the air, decompose a portion of 
the sugar into alcohol and carbonic acid gas. The lat- 
ter bubbles up through the mixture. This occurs within 
three or four hours after the mixture of flour and water 
is put into a moderately warm place. If it is desired that 
the fermentation should take place more quickly, yeast 
is added. By this means large numbers of active germs 
are at once introduced into the liquid, and the destruc- 
tive changes begin immediately. 

The alcohol formed in bread is driven off by the heat 
of the oven in baking, so that no harm is done by it, al- 
though in its formation a portion of the sugar which the 
flour contained has been destroyed, and there have been 
formed, besides the alcohol, minute quantities of other 
substances having unpleasant flavors. Hence fermented 
bread is in some respects inferior to unleavened bread. 

135. Wine - making. — The manufacturers of alco- 
holic drinks likewise employ two general methods in 



72 SECOND BOOK IN PHYSIOLOGY. 

their production. The juices of sweet fruits — as grapes, 
apples, pears, and cherries — are fermented by the action 
of germs received from the air or carried upon the sur~ 
face of the fruit. By this means various kinds of wine, 
cider, perry, and similar drinks are produced. The 
amount of alcohol contained in wine or cider depends 
upon the amount of sugar contained in the fruit. Not 
infrequently a quantity of sugar is added to the nat- 
ural fruit juice, so as to produce a large quantity of 
alcohol. The manufacturer uses great care to stop the 
fermentation at the right moment ; otherwise, as we have 
already learned, the alcohol would be decomposed into 
vinegar and w r ater. 

In different countries fermented drinks are made from 
various substances. In some tropical countries palm- 
wine is made by fermenting the sweet juice of the palm- 
tree. In Mexico the juice of the cactus is fermented. 
In Western Asia fermented milk, called koumiss, is as 
popular a beverage as is beer in Germany or wine in 
France. 

136. Malt Liquors. — The manufacture of beer and 
ale is a more complicated process. The proportion of 
sugar naturally contained in the grains from which alco- 
hol is commonly made is so small that their use for the 
manufacture of alcoholic drinks would be unprofitable 
without some means of increasing it. The grains con- 
tain starch in abundance. To convert this into sugar the 
brewer takes advantage of a natural process, by which 
sugar is produced from starch for a purpose quite dif- 
ferent from that for which he desires it. Nature stores 
up the starch in grains, as well as in most other seeds, 
for the purpose of furnishing a supply of food to the lit- 
tle plantlet before it has acquired roots and leaves with 



STIMULANTS AM) NARCOTICS. 73 

which to gather food from the air and the soil. In the 
process of germination, or sprouting, this starch is con- 
verted into sugar, from which the plantlet forms its first 

roots and the beginning of the stem. 

Taking advantage of this fact, the brewer moistens 
the rye, barley, or other grain from which he proposes to 
manufacture alcohol, and then exposes it to a warm at- 
mosphere. As the result, the grain sprouts, just as it 
would have done had it been planted in the earth. The 
brewer watches this process carefully until the sprout 
sent out by each kernel has attained a length which his 
experience shows him to indicate that the largest pos- 
sible amount of starch has been converted into sugar. 
lie then dries the grain, and by this means the growth of 
the sprout is stopped. Then, by soaking the grain with 
water, the sugar is dissolved out. This process is known 
as malting. 

The sweet liquid obtained by the malting of grain is 
fermented by the addition of yeast. Beer, ale, stout, 
porter, and other alcoholic drinks manufactured in this 
way, are called malt liquors. As formerly made, the 
amount of alcohol contained in these liquors depended 
upon the amount of sugar or starch furnished by the 
grain from which they were made. At the present 
time glucose, a sugar made from corn by a chemical 
process, is very largely used in the manufacture of malt 
liquors, so that the amount of alcohol which malt liquors 
now contain is often very much larger than in those made 
before the cheap manufacture of glucose was introduced. 
It is thus evident that the malt liquors now manufactured 
are more intoxicating than those formerly made. 

137. Distillation. — The strong liquors — brandy, 
whiskey, gin, and rum — as well as ordinary alcohol are 
4 



74 SECOND BOOK IN PHYSIOLOGY. 

made from fermented liquids by a process known as dis- 
tillation. Many substances can be distilled. The process 
consists in heating the liquid or other substance until it 
is converted into a vapor, and then condensing the va- 
por by cooling it until it is reduced to its original state. 

A familiar example of distillation may be seen in the 
boiling of water in a teakettle. The steam w T hich issues 
from the spout of the teakettle is water in the form of 
vapor. If by means of a rubber tube this vapor is led 
into a bottle or other vessel surrounded by ice, it will 
be cooled and condensed to the liquid form, and will ap- 
pear as distilled water. By holding a glass filled with 
ice near the spout of the teakettle, a few drops of dis- 
tilled water w T ill quickly condense upon the sides of the 
glass. If the glass is held, instead, to the nose of a tea- 
pot containing boiling tea, the liquid which condenses 
upon the sides of the glass will be found to have the 
flavor of tea, showing that some portion of the tea was 
distilled with the water. (See Experiment 4, p. 271.) 

It is in a manner precisely similar that alcohol is dis- 
tilled. A large vessel containing the fermented liquid is 
heated, and the vapor which rises is conducted through 
a long coil of copper pipe called a still, w^hich is kept con- 
stantly cooled, so that the vapor is condensed. Alcohol 
readily becomes a vapor at a lower temperature than that 
at which water boils, and thus, by carefully regulating 
the heat, the alcohol may be separated from the water. 
The first time it is distilled, a considerable amount of 
water passes off with the alcohol ; but by repeated dis- 
tillations the alcohol may be obtained in a nearly pure 
state. It is by distillation that strong liquors are made. 
Brandy is the liquor obtained by distilling the fer- 
mented juice of grapes and other fruits. Whiskey is 



STIMULANTS AM) NARCOTICS. T:> 

distilled from beer. Gin is generally made by mixing 

oil of juniper and other substances with alcohol. Bum 
is made by the distillation of fermented cane-juice with 
molasses and water. In some countries whiskey is dis- 
tilled from an alcoholic liquor obtained by fermenting 
potatoes. Distillation has probably been practised by 
the Chinese from very ancient times, but was first known 
among civilized nations about seven hundred years ago. 

From what we have learned, it is apparent that al- 
though alcohol is made from fruits, grains, and other 
substances used as food, it is not naturally found in 
foods, but is the result of processes which change the 
wholesome elements of the food into a harmful and 
poisonous substance. It is also evident that the essen- 
tial difference between the various kinds of alcoholic 
drinks is merely in the proportion of alcohol which they 
contain. Thus, brandy, whiskey, gin, and rum are from 
two fifths to three fifths alcohol; wine, one tenth to one 
fifth; cider, one twentieth to one tenth; beer and ale, 
one twenty-fifth to one sixteenth. Small beer contains 
two or three parts in a hundred of alcohol. 

13S. Cider. — From the above it will be seen that 
cider, which is by many hardly considered an intoxicat- 
ing liquor, contains more alcohol than beer, and as much 
as some kinds of wine. Apple- juice, like the juice of the 
grape, when first expressed from the fruit, is entirely 
wholesome ; but within a few hours fermentation is set 
up by the germs which the liquid receives from the air 
and from the fruit itself. Alcohol is thus formed, the 
quantitv increasing until all the sugar present has been 
converted into alcohol and carbonic acid gas. 

139. Hard Cider is a very intoxicating beverage, 
and produces a very bad form of intoxication. What is 



76 SECOND BOOK IN PHYSIOLOGY. 

called new or sweet cider often contains a considerable 
amount of alcohol. If the amount is not sufficient to 
produce intoxication, it may be sufficient to produce an 
appetite for alcoholic beverages, which will probably lead 
to the use of stronger liquors. Many persons have be- 
come confirmed drunkards in this way. It is quite diffi- 
cult to tell the exact moment at which cider changes 
from a harmless to a dangerous beverage. When the 
liquid effervesces, as it is certain to do after it is a few 
hours old, it invariably contains alcohol. 

140. The Alcohol Family. — There are several oth- 
er substances besides that commonly known as alcohol, 
which are known to the chemist by this name. Some 
of these are formed with ordinary alcohol in the fer- 
mentation of malt liquors. 

♦ 141. Fusel-oil. — One of the most poisonous of these 
substances is fusel-oil. This poison is always present in 
crude alcohol, and in whiskey and other strong liquors 
when first distilled ; but the greater portion is generally 
removed by a special process of purification. This is fre- 
quently so imperfectly done, however, that more or less 
of this poison is suffered to remain in the liquor. Fusel- 
oil is much more poisonous and intoxicating than ordi- 
nary alcohol, and whiskey containing it is very deadly 
in its effects. Large quantities of this sort of liquor are 
shipped to Africa, where, to the shame of the civilized 
nations sending it, thousands of the natives are annu- 
ally destroyed by its use. 

Another member of the alcohol family is the liquid 
commonly known as wood naphtha. This is also intoxi- 
cating, though somewhat less so than ordinary alcohol. 
It is sometimes resorted to by persons addicted to drink, 
when ordinary alcoholic liquors are withheld from them. 



STIMULANTS AND NARCOTICS 77 

The fact that ordinary alcohol is one of a family of 
substances scientifically known as alcohols, all the mem- 
bers of winch are both poisonous and intoxicating, is cer- 
tainly much against its character. If there were no other 
evidence upon the subject, it could hardly be considered 
credible that this one member of so bad a family should 
be a wholesome substance while the others are so very 
poisonous. Any person who should become addicted to 
the use of naphtha, or of mixtures containing this sub- 
stance, would certainly be regarded as quite beside him- 
self ; yet it is a fact, well settled by experiment, that 
naphtha is less intoxicating and less poisonous than the 
form of alcohol so commonly employed in the various 
alcoholic drinks. 

142. How Alcohol Behaves. — Alcohol is a chem- 
ical substance, and is capable of combining chemically 
with various substances, in which respect it differs in 
a very marked manner from foods. If lighted, alcohol 
burns like naphtha, kerosene-oil, etc. 

Meat and other substances, which naturally decay 
readily, may be preserved for an indefinite period if 
placed in alcohol. From this fact alcohol is called an 
antiseptic. Ignorant persons sometimes imagine that be- 
cause alcohol will preserve a dead body from decay, it 
may also be useful as a means of preserving life. Noth- 
ing could be more erroneous than this reasoning. Many 
chemical agents are antiseptics — that is, will prevent de- 
cay — simply because they destroy the germs by which 
decay is caused. The same properties which make them 
destructive to germs, the lowest form of life, make them 
destructive to human beings, who exhibit life in its high- 
est form. 

Alcohol possesses a remarkable affinity for water — so 



78 SECOND BOOK IN PHYSIOLOGY. 

great that it is very difficult to obtain it wholly free 
from water. If pure alcohol is exposed to the air, it 
very rapidly absorbs water from the atmosphere, and so 
becomes diluted. It also absorbs water from everything 
with which it comes in contact. It is partly hy means 
of this avidity for water that alcohol works such mis- 
chief in the human body. (See Experiment 5, page 272.) 

143. Alcohol a Poison to Plants. — The active 
part of a living cell is transparent. A cell to which 
alcohol has been applied quickly loses its transparency 
and dies. This is true of both animal and vegetable 
cells. If the roots of a plant are placed in a vessel con- 
taining water, the plant will remain fresh for some time ; 
but if the water contains even a small amount of alcohol, 
the plant soon dies. Plants, the roots of which were 
placed in cider or beer, were dead in less than three days. 

Professor Darwin made an interesting experiment for 
the purpose of ascertaining the effect of alcohol upon 
an insectivorous plant, a variety- of drosera. The plant 
was placed under a jar, beneath which was also placed 
a teaspoonful of alcohol in a watch-glass. In twenty -five 
minutes the plant was removed, when it showed no signs 
of life, and the next morning all but one of its leaves 
were found to be entirely dead. 

141. Alcohol a Poison to Animals. — AVe may 
learn something of the effects of alcohol upon the deli- 
cate tissues of an animal by applying it to an egg. (See 
Experiment 6, page 272.) The egg will look as though it 
had been boiled. Alcohol produces a similar effect upon 
muscles, nerves, blood, and every living tissue with which 
it comes in contact. Pure alcohol is almost as deadly a 
poison as strychnia or prussic acid. A few ounces of 
pure alcohol will kill a dog in a very short time. Small 



STIMULANTS AND HARCOTK 70 

doses prove rapidly fatal to such small animals as 
leeches and minnows. (See Experiment 7, page 272.) 
Earthworms wet with alcohol die very quickly. Alcohol 
is equally fatal to insects. Flies put into a bottle with 
alcohol are killed by its vapor. 

Dr. Percy administered two and one -half ounces of 
alcohol to a full-grown dog. The animal uttered a loud 
cry and fell lifeless to the ground. Another physician 
caused a small dog to be intoxicated daily by a half- 
ounce of pure alcohol. After a time it became very 
thin, and at length died in a condition of partial paraly- 
sis. A French physician found that fowls died after tak- 
ing one and one-half teaspoonfuls of brandy daily for a 
few weeks. A few years ago a newspaper correspond- 
ent reported the death of a goat from beer -drinking. 
Some beer manufacturers had been experimenting upon 
the animal to test the quality of their beer, which was 
well shown by the result. It was reported that the 
parties were arrested under the law prohibiting cruelty 
to animals, but they were allowed to continue dispen- 
sing their beer to human beings. 

115. Alcohol a Poison to Human Beings. — It 
would naturally be expected that a substance which is 
poisonous to plants and to all kinds of animals would be 
equally poisonous to human beings, whose tissues are 
composed of essentially the same kind of living sub- 
stance as those of animals. The results of the experi- 
ments made upon animals are constantly confirmed by 
the experience of thousands of unwise human beings, 
who are daily experimenting upon themselves. Nu- 
merous cases are recorded in which grown persons and 
children have been killed, sometimes almost instantly, 
by drinking strong alcoholic liquors. 



80 SECOND BOOK IN PHYSIOLOGY. 

Professor Christison gives an account of a man who 
stole a bottle of whiskey, and, to avoid detection, drank 
the whole of it at once. In four hours he was dead. 
Sir Astley Cooper, the celebrated English surgeon, said, 
" Spirits and poisons are synonymous terms." Profess- 
or Christison and other writers upon poisons mention 
alcohol among the " narcotic acrid poisons." 

The special effects of alcohol upon the heart, lungs, 
nerves, and other parts of the body, will be described in 
connection with the study of these organs. Let us now 
consider the particular effects of alcohol upon the or- 
gans and processes of digestion. 

146. Effects of Alcohol upon the Stomach. — One 
of the effects of alcohol upon the stomach may be in- 
ferred from its effects upon the mucous lining of the 
mouth. If the liquor is at all strong, the first sensation, 
when a portion is taken into the mouth, is that of burn- 
ing and irritation. If retained in the mouth a little time, 
a sensation of numbness is experienced, showing that the 
nerves are benumbed or paralyzed. When taken into the 
stomach, alcohol produces similar effects. The " warm- 
ing" sensation in the stomach which drinkers enjoy is 
really an evidence of irritation. 

If a cloth is moistened with a little pure alcohol, then 
laid upon the skin and covered with a piece of oiled 
silk, the effect produced will be much the same as that 
of a mustard plaster. The effect of strong alcohol upon 
the stomach is similar, only the stomach protects itself 
so far as it can by pouring out mucus to cover its lin- 
ing membrane. Strong alcoholic drinks paralyze the 
glands w r hich secrete the gastric juice, and the muscles 
which contract upon the food. 

A hard drinker often has no appetite, and takes no 




EFFECTS OF ALCOHOL UPON THE 
STOMACH. 

A. Healthy Stornach; B. Congested Stomach of a 
moderate drinker. 



Plate TIL 



80 -A 



STIMULANTS AND NARCOTICS 81 

food for several days. His stomach is paralyzed, so that 
it cannot digest food. His strength is not kepi up by 

alcohol, however, for he becomes very weak, and his dis- 
sipation often ends in an attack of inflammation of the 
stomach or delirium tremens. These facts show the fol- 
ly of taking wine or other liquor as an aid to digestion. 

147. Dr. Beaumont's Experiments. — Dr. Beau- 
mont had a remarkable opportunity for observing the 
exact effect of alcohol upon the stomach, in the case of 
Alexis St. Martin, the inside of whose stomach could be 
examined through an opening. St. Martin sometimes in- 
dulged in what is commonly termed a " spree." On 
one of these occasions, when he had been drinking liquor 
freely for several days, Dr. Beaumont found the lining 
of his stomach in a state of inflammation and ulcera- 
tion, although, strange as it may appear, he complained 
of no discomfort. Each day the condition grew worse, 
however, and after a few days he began to suffer some 
pain and tenderness at the pit of his stomach, dizziness, 
and dimness of vision on stooping down and rising again. 
He had a coated tongue, and his countenance was sal- 
low. On looking into his stomach again, Dr. Beaumont 
found the mucous membrane covered with dark spots, 
and a large amount of mucus mixed with blood. The 
discharges from the bowels were like those in dysentery. 

The abnormal secretion of mucus temporarily occa- 
sioned by alcohol becomes constant when strong liquors 
are habitually used, and thus catarrh of the stomach is 
induced — a disease very common among those who use 
alcoholic drinks. 

liS. Alcoholic Dyspepsia. — Dyspepsia, or indi- 
gestion, is almost universal among habitual users of 
strong alcoholic drinks. This is exactly what would be 
4* 



82 SECOND BOOK IN PHYSIOLOGY. 

expected of an agent which not only irritates and in- 
flames the stomach, but benumbs and paralyzes it, and 
impairs the activity of the gastric juice. Dr. Roberts, 
an eminent English physiologist, has shown by experi- 
ments that alcohol does not aid digestion, as once 
thought, but hinders it, even when taken in small quan- 
tities. Singularly enough, Dr. Roberts concludes from 
this fact, not that alcohol is a harmful agent, but that 
we are in danger of great injury from too active di- 
gestion, and that we require alcohol to slow down 
the digestive process to a safe rate ! ! This is an excel- 
lent illustration of the absurd arguments which even 
learned men sometimes offer in support of alcohol. Ex- 
periments recently made by the author showed that 4 oz. 
of claret diminished the work of digestion one half, 
while 2 oz. of brandy nearly suspended it. 

B. W. Richardson, M.D., F.R.S., asserts that "as the 
result of using alcohol there is engendered a perma- 
nent disorder, which, for politeness' sake, is called 
dyspepsia, and for which different remedies are often 
sought but never found. 'Anti-bilious pills,' whatever 
the term may mean; ' Seidlitz- powders,' 'effervescing 
waters,' and all the aids to further indigestion in which 
the afflicted who nurse their own diseases so liberally 
and innocently indulge, are tried in vain." 

149. Cancer of the Stomach. — This horrible and 
hopeless disease, while not confined to those who use 
alcoholic liquors, is known to be much more frequent 
among intemperate persons than among abstainers. 

150. The Gin Liver. — This is the name applied by 
pl^sicians to a condition of the liver in which the organ 
becomes greatly shrunken and covered with little nod- 
ules, from which it has been given the name of " hob- 



STIMULANTS AND NARCOTICS. 83 

nailed liver," as its surface resembles the sole of an Eng- 
lish cartman's shoe filled with hobnails. This form of 
disease, which renders the liver useless and finally pro- 
duces death, is a frequent result of the use of strong 
liquors. Fatty degeneration of the liver, in which the 
liver becomes changed to a mass of fat, sometimes enor- 
mously enlarged, is another consequence of indulgence in 
alcohol. This disease occurs in beer-drinkers as well as in 
those who use strong liquors. 

Examination of the bod\ T of a man who has died in a 
state of intoxication, shows a larger amount of alcohol 
in the liver than in any other part. This is due to two 
facts : (1) All the alcohol absorbed from the stomach 
enters the portal vein, and hence is carried directly to 
the liver ; (2) The liver endeavors to protect the rest of 
the body from the injurious effects of alcohol, as well 
as of many other poisonous substances, by absorbing 
and retaining within itself as much of the poison as 
possible. It is thus apparent that, next to the stomach, 
the liver is most exposed to injury from the use of al- 
cohol ; and it is anything but marvellous that the beer- 
drinker and wine -bibber should habitually suffer from 
inactivitv of the liver, " biliousness," and various de- 
rangements of this important organ. 

151. Is Alcohol a Food? — It appears from what 
we have already learned respecting this drug that there 
can be little room for the discussion of this question. 
It is certainly incredible that any substance may be 
both food and poison at the same time. The essen- 
tial uses of food are to furnish to the body material for 
the repair of its tissues, and to maintain the supply of 
force and heat. Alcohol cannot be assimilated, and 
hence does not replenish the tissues. When first ad- 



84 SECOND BOOK IN PHYSIOLOGY. 

ministered, it sometimes occasions an apparent increase 
of heat, by causing the blood to accumulate at the sur- 
face. But, in consequence of this, the body loses heat 
very fast, so that in a little while it is cooler than be- 
fore. It has been claimed that as alcohol is oxidized — 
that is, disappears in the body by combining with oxy- 
gen — it must be useful as a means of supplying heat ; 
but the practical fact that the body becomes cooler un- 
der the influence of alcohol proves clearly that this drug 
is of no value as a source of heat, even if some small 
amount may be oxidized. 

Alcohol does not make a person stronger. It acts just 
as a whip or a spur acts upon a tired horse. No one 
would venture to assert that a whip really makes a 
horse stronger, although it makes him appear stronger. 

A small amount of alcohol, not more than three or 
four drachms in twenty-four hours, disappears within the 
body ; but it has by no means been established that the 
oxidation of alcohol, upon which its claim to value as a 
food rests, takes place in either the blood or the tissues, 
or in any manner useful to the body. Dr. Richardson 
suggests that the alcohol may be largely thrown out in 
the bile by the liver, and oxidized in the intestinal ca- 
nal, the products of oxidation being afterwards absorb- 
ed. If this theory is established by actual experiments, 
the vexed question will be forever settled. The great 
chemist Liebig remarked that the amount of nutriment 
in a hogshead of the best Bavarian beer is less than 
that contained in a single loaf of bread, — a statement 
which will undoubtedly surprise those who have been 
taught to look upon beer and ale as valuable foods. 

The claim has been made that alcohol lessens the 
wastes of the body, and so economizes food, and is thus 



STIMULANTS AND NARCOTICS. 85 

a kind i)\' substitute for food. This claim is disputed by 
the late Dr. Smith, of England, an eminent authority 
on foods; but if it be true that alcohol lessens waste, 
this fact does not establish its claim to the dignity of an 
article of diet. What we desire of food is not that it 
shall diminish waste, but that it shall replace what is lost 
by work; for it is only by using up material that the 
body can manifest force, or that any kind of vital work 
can be performed. To lessen natural waste is to lessen 
life. Alcohol deadens and paralyzes, and thus lessens 
the activity of the nerves and of the little cell-workers 
with which it comes in contact in the body, and so di- 
minishes vital work. 

Careful experiments made by Dr. Parkes, of England, 
and others, show that the use of alcohol actually les- 
sens muscular strength. Experiments made by Professor 
N. S. Davis, M.D., of Chicago, and Dr. B. W. Richard- 
son, of London, show very conclusively that alcohol 
lessens rather than increases animal heat. The tem- 
perature of a drunken man is sometimes several de- 
grees less than that of a person in health. 

If further argument is needed, we may adduce the 
fact that alcohol is by no means the only substance that 
will lessen waste. It is well known that opium possesses 
this property ; and arsenic, one of the most dangerous of 
poisons, has been shown by the experiments of Schmidt 
and Sturzwage, two German physiologists, to possess 
the same properties as alcohol in this particular; yet 
no one would think of calling either arsenic or opium a 
food on this account. It is very plain that the argu- 
ment that alcohol economizes food is brought forward 
simply as an apology for indulgence in alcoholic bever- 
ages, since those who urge it most are not those who 



86 SECOND BOOK IN PHYSIOLOGY. 

need to avail themselves of its use on the score of econ- 
omy. Again, the utter folly of this mode of economiz- 
ing, allowing the claim for alcohol as a food substitute 
to be established, becomes apparent when we stop to 
consider the fact that alcohol, in the form of any com- 
mon drink, costs many times more than the food which 
it is supposed to save. 

152. The Alcohol Appetite. — After any narcotic 
or stimulating drug has been used for some time, the 
system becomes habituated to it, and an intense desire 
for the accustomed drug is experienced whenever it is 
not taken, or when the usual quantity cannot be obtained. 
This is especially true of alcohol, opium, and tobacco. 
Another fact of importance is that all drugs of this class 
create an increasing demand for the particular drug 
which has been habitually taken, so that it must be 
taken in increasing quantity. It is in this way that the 
alcohol appetite, the opium habit, the tobacco habit, and 
the tea-and-coffee habit are formed. 

The use of alcohol, opium, or any other " vice-drug " 
in small doses will in time produce a demand for large 
doses. It is in this way that the use of beer, wine, or 
cider leads to the use of stronger liquors. 

153. Moderate Drinking. — Many persons argue 
that the injury done by alcohol is due only to its exces- 
sive use. There are two facts which show the great 
danger of moderate drinking : 1. The use of alcohol in 
small quantities, often — we may perhaps say usually — 
leads to its use in larger quantities, in consequence of 
the formation of the alcohol appetite. After small 
amounts of alcohol have been used for a time, larger, 
stronger, or more frequent drinks must be taken to pro- 
duce the same effects, and thus the moderate drinker 



STIMULANTS AND NARCOTICS. 87 

becomes, it* not a sot, a hard drinker, taking quantities of 

alcoholic liquor which at first he would have considered 
very dangerous. 2. Many of the worst effects of the use 

of alcohol are to be seen in moderate drinkers. The de- 
structive changes by which the normal structures of the 
vital organs are so changed as to disable them, thus 
causing serious and incurable maladies, are frequently 
found in persons who consider themselves very temper- 
ate, and who have never been intoxicated in their lives. 

Said the eminent Sir Henry Thompson, a famous 
London surgeon, " I have no hesitation in attributing a 
very large proportion of some of the most painful and 
dangerous maladies which come under my notice, as 
well as those which every medical man has to treat, to 
the ordinary daily use of fermented drinks, taken in the 
quantity which is commonly deemed moderate." 

Careful records have been kept for many years by 
life-insurance companies, both in this country and in 
England. The statistics derived from these records 
show that human life is greatly shortened by the habit- 
ual use of alcohol, even in what is termed " moderation." 

154. "Bitters." — Many persons are unsuspectingly led 
into habits of intemperance by the use of various kinds 
of patent medicines advertised as "bitters" "tonics" 
etc. Few, if any, of these mixtures are free from alco- 
hol. Some that are said to be free from alcohol, and 
on that account are called " temperance bitters," act- 
ually contain more alcohol than some which make no 
such claim. Some of the most popular of these nos- 
trums contain as much alcohol as the strongest liquors. 
u Jamaica ginger " contains so much alcohol that it will 
burn in a spirit-lamp. The habitual use of these com- 
pounds is quite as harmful as the use of alcohol in any 



88 SECOND BOOK IN PHYSIOLOGY. 

other form, and sometimes even more injurious on ac- 
count of the presence of other harmful drugs. 

155. Alcohol in Cookery. — The use of alcohol in 
cookery is one way in which the appetite for alcohol 
is cultivated. Sauces, jellies, preserves, and similar prep- 
arations, when they contain wine, brandy, or other alco- 
holic liqnors, have a most pernicious influence, and often 
lay the foundation for a life of intemperance. Alcohol 
and kindred drugs are dangerous poisons. They destroy 
the lives of thousands every year ; and even when taken 
at first in small quantities, they often produce a fatal 
fascination from which the unfortunate victim never 
escapes. 

156. Alcoholic Candies. — Candies and confections 
of various sorts often contain alcohol in the form of 
wine or brandy. The use of such candies may readily 
produce an appetite for alcohol in other and stronger 
forms. Children have been found in a state of partial 
intoxication as the result of eating freely of such candies. 

The only safe rule for a person who desires to lead a 
temperate life is to avoid everything which contains al- 
cohol in any form. Any other course is most unsafe ; 
for the alcohol appetite is often formed unconsciously, 
and is only recognized when it has become fully devel- 
oped, and has attained the complete mastery. 

157. Absinthe. — This is an exceedingly poisonous and 
intoxicating liquor, made by adding the oil of wormwood 
to alcohol. It has long been very extensively used in 
France and Switzerland. Recently it has been intro- 
duced into this country and England. Absinthe pro- 
duces the same results as alcohol, with other and even 
worse effects, due to the poisonous oil which it contains. 
The stomach and the nerves are especially injured by it. 



STIMULANTS AND NARCOTICS. 89 

Its victims are short-lived, and die miserably and with 
great suffering. 

158. The Origin of Tobacco - using. — Tobacco- 
nsing was first witnessed by Columbus when he dis- 
covered America. In his description of his discoveries 
he stated that he saw "the naked savages twist huge 
leaves together and smoke like devils." Is it not strange 
that civilized men should ever have desired to imitate 
the example of those degraded savages? 

Smoking, chewing, and snuff -taking — the principal 
methods of taking tobacco — all originated with the 
Indians who inhabited this continent centuries ago ; 
and these practices undoubtedly helped to bring them 
to the wretched condition in which Columbus and other 
explorers found them. Civilized man has made no im- 
provement in the practice of tobacco using. 

The use of tobacco was recognized as an evil soon 
after its introduction among civilized nations. Kings 
issued proclamations and made laws against it. The 
Pope issued a "bull" against it, and the Sultan of Tur- 
key caused a man convicted of smoking to be led through 
the streets of Constantinople with his nose slit and the 
stem of his pipe thrust through it, as a warning to other 
users of the weed. 

Tobacco contains an essential oil, nicotine, which is a 
powerful narcotic and a very deadly poison. A drop of 
nicotine placed upon a cat's tongue caused immediate 
insensibility, and death in two minutes. One tenth of 
a drop killed a frog in a few seconds. A strong cigar 
contains enough of this poison to kill two men, if taken 
at a single dose. 

The use of tobacco for the destruction of insects in 
greenhouses is a familiar illustration of its deadly prop- 



90 SECOND BOOK IN PHYSIOLOGY. 

erties. Professor Darwin has also shown, by experi- 
ments upon insectivorous plants, that nicotine is a poi- 
son to plants as well as to animals. 

The poisonous properties of tobacco are well shown 
in the effects upon a person not accustomed to its use. 
The deathly pallor and the extreme nausea and prostra- 
tion are evidences of its deadly properties. A man once 
undertook to smuggle a quantity of tobacco by binding 
it about his body next the skin. He was taken sudden- 
ly so ill that his crime w r as discovered. Cowardly sol- 
diers have been known to make themselves sick upon 
the eve of a battle by placing tobacco leaves next the 
skin, under the arms, or over the stomach. Deaths from 
the use of tobacco are frequently reported in the news- 
papers, and medical literature records many instances of 
this sort. 

159. Tobacco Dyspepsia. — When tobacco is chewed, 
a part of the poison is absorbed : some is also swallowed. 
The portion which is swallowed poisons the digestive 
fluids, so that their work is less perfectly done than it 
otherwise would be, and hence dyspepsia is a very com- 
mon disorder among tobacco-chewers. 

160. Smoker's Sore Throat. — The mouth and throat 
are sure to suffer from the use of tobacco. At first, dry- 
ness and unnatural thirst are produced, especially by 
smoking, and frequently this is the inducement to in- 
dulge in alcoholic drinks. After a time, a chronic in- 
flammation is produced, which bears the significant 
name of "smoker's sore throat" a disease with which 
all physicians are familiar. This disease is absolutely 
incurable so long as the use of tobacco is continued, 
and often causes deafness, by extension of the disease to 
the ears. 



STIMULA.NTS AND NARCOTICS. 91 

161, Tobacco Cancer. — This dreadful disease usual- 
ly affects the lips, tongue, or throat. It seldom occurs 
except in smokers. AVomen rarely have cancer of the 
lip, at least in this country. This is because very few 
women smoke. 

Every surgeon of experience has met with cases of 
cancer of the tongue or lip arising from this cause. It 
is rare, indeed, that cancer occurs in these parts of the 
body from any other cause. 

Many other grave diseases are due to the use of to- 
bacco ; but, besides the harm which it does to the body, 
it is a gross and uncleanly practice, and often has a 
most pernicious influence upon the mind and morals. 
Most tobacco-users show little regard for the feelings 
of those who do not use the weed, but soil the air which 
others must breathe, and defile with spittle the floor or 
pavement over which others must walk, apparently with 
no thought but for the gratification of their own selfish 
and unnatural appetite. 

162. Tea and Coffee. — These popular beverages, 
generally considered quite harmless, must be included 
in the list of harmful drinks, although the injury arising 
from their use is not to be compared with that grow- 
ing out of the use of alcohol and tobacco. Tea consists 
of the dried leaves of a shrub which grows in China 
and India. The leaves are picked when young, and 
dried by artificial heat. Coffee consists of the berries 
of the coffee-tree, a native of Arabia, now cultivated in 
the East and the AVest Indies, South America, and other 
tropical and sub-tropical countries. 

Tea and coffee are used chiefly for the mildly stim- 
ulating or narcotic effects which they produce. This 
property is due to a peculiar substance contained in both 



92 SECOND BOOK IN PHYSIOLOGY. 

tea and coffee, known as theine in tea and caffeine in 
coffee. Both tea and coffee also contain tannin and 
peculiar aromatic substances to which their flavors are 
due. (See Experiment 8, page 272.) 

163. Harmful Effects of Strong Tea and Coffee. 
Theine is a powerful narcotic poison. One seventh of a 
grain will kill a frog. Five grains will kill a cat. Eight 
grains administered to a man produced severe poison- 
ous symptoms. Dr. Edward Smith, of England, and his 
assistant were made insensible by drinking, as an exper- 
iment, a quantity of coffee made from two ounces of 
coffee-beans. Tea contains a very large amount of the- 
ine, the proportion being from three to six per cent. 
An ounce of tea-leaves contains from fifteen to thirty 
grains of theine, an amount sufficient, if extracted and 
swallowed at once, to poison a person not accustomed 
to its use. The tannin found in both tea and coffee is 
also harmful. It injures the stomach, delays digestion, 
and hinders absorption. 

An English officer, while on duty in Africa a few 
years ago, lost a fine horse by poisoning with tea, a 
quantity of w r hich was accidentally mixed with the ani- 
mal's food. The effect of the tea upon the animal was 
thus described : " The animal plunged and kicked and 
ran backward, at intervals galloping madly round, final- 
ly falling into a donga, where it lay dashing its head 
on the rocks, and w^as despatched by an assegai thrust 
through the heart. The post-mortem appearances indi- 
cated extreme cerebral congestion." 

164. Tea-drinker's Dyspepsia. — An eminent phy- 
sician stated before the British Medical Association, a 
few years ago, that in his practice in Australia he had 
found dyspepsia from the use of tea and coffee exceed- 



STIMULANTS AND NARCOTICS. 93 

ingly common. Many English physicians and numerous 
medical authorities in this country have also observed 
the same fact. Dr. Roberts, a renowned English phys- 
iologist, lias shown that digestion is hindered by both 
tea and coffee. 

Tea-drinkers are especially liable to a form of stomach 
disorder commonly known as sick-headache. Dr. James 
Frazer, of Scotland, has recently conducted a series of 
experiments to determine the effects of tea, coffee, and 
cocoa upon digestion, and finds that the effect of all of 
them is to retard digestion. Says B. W. Richardson, 
M.D., F.R.S. : "The extremely injurious effects of tea are 
best seen in some of those who are charged with the com- 
mercial duty of ' tea-tasting.' A professional tea-taster 
who was so seriously affected by the process that he 
thought it proper to consult me on the symptoms in- 
duced, defined the symptoms very clearly as follows : 
'Deficiency of saliva, destruction of taste for food, bil- 
iousness, nausea, constipation, an extreme and undefin- 
able nervousness, and nightmare whenever sleep is ob- 
tained.' ' Says Prof. J. W. Morton, M.D., an eminent 
specialist in nervous diseases : " I am forced to think 
that many people, unconsciously to themselves and to 
their physicians, suffer from a train of symptoms due 
to tea (or its congener, coffee). We often find peo- 
ple taking tea to relieve the very set of symptoms 
which its abuse produces ; and it is often the fact that 
patients date their recovery from a dyspepsia or nerve 
exhaustion from the time when they gave up their 
tea." 

165. Tea and Coffee not Foods. — Tea and coffee, 
as ordinarily used, furnish so little nourishment that they 
cannot be classed as proper foods. They lessen both the 



94 SECOND BOOK IN PHYSIOLOGY. 

desire for food and the ability to digest it. They con- 
tain no nourishment, aside from the small amount of 
milk and sugar usually added. 

" The cups that cheer, and not inebriate," is an expres- 
sion often incorrectly used respecting these beverages. 
Dr. Arlidge, of England, asserts that "tea drunkards" 
are numerous among the poor women of some parts of 
that country. In South America, a person who is ad- 
dicted to the free use of coca -leaves, which also con- 
tain theine, is termed a coquero, which means the same 
as the word drunkard with us. Two women were ar- 
rested for drunkenness in Boston not long since, who 
proved to be tea drunkards. They had acquired the 
habit of chewing tea, and had consumed so great a 
quantity as to produce intoxication. 

The Saracens were about the only Eastern nation 
who did not adopt the use of tea and coffee, as well as 
alcoholic drinks and other narcotics. A writer in the 
International Review says of this remarkable people : 
" The Western Saracens abstained not only from wine, 
but from all fermented and distilled drinks whatsoever, 
were as innocent of coffee as of tea and tobacco, knew 
opium only as a soporific medicine, and were inclined 
to abstemiousness in the use of animal food. Yet six 
millions of these truest sons of temperance held their 
own for seven centuries against great odds of heavy- 
armed Giaours ; excelled all Christendom in astronomy, 
medicine, agriculture, chemistry, and linguistics, as well 
as in the abstract sciences, and could boast of a whole 
galaxy of philosophers and inspired poets." 

166. Cocoa and Chocolate. — These beverages con- 
tain a substance similar to theine, known as theobro- 
mine, the properties of which are essentially the same as 



STIMULANTS AND NARCOTICS. 95 

those of theine, though usually present in much smaller 

amount. 

167. Chloral, Opium, Cocaine, and other Nar- 
cotics. — These substances, with which may be included 
hashish^ or Indian lump, and other similar drugs, when 
habitually used, are the cause of great injury to the di- 
gestive organs, as well as to the entire system. Chlo- 
ral and opium are largely used in this country, as well 
as elsewhere, and their use seems to be increasing. 
They are deadly drugs, and their habitual use inevitably 
leads to physical, mental, and moral ruin. 

During many years' experience as superintendent of 
a large sanitarium and hospital, the writer has met 
many cases illustrative of the profound mischief wrought 
by these narcotic drugs, the use of which has given rise 
to what might be termed the poison -habit; for it is 
rare indeed that a person is found addicted to one only 
of these narcotic drugs. In such cases, the victim of a 
poison-habit must give up the use of all narcotics in 
order to be reformed from the one to which he may be 
chiefly enslaved. 

SUMMARY. 

1. All narcotics are poisons. Those in most common use are alco- 
hol, tobacco, opium, tea, and coffee. 

2. Alcohol is produced by fermentation. Pure alcohol and strong 
liquors are made by the distillation of fermented liquors. 

3. Alcoholic beverages contain from two to sixty per cent, of alcohol. 

4. Cider, when "hard," is a very intoxicating liquor. 

5. Alcohol is a member of a large family of substances of similar 
character, poisonous and intoxicating. Wood naplitlia and fusel -oil 
are alcohols. 

6. Alcohol is a poison to plants and animals, as well as to human 
beings. 

7. The effects of alcohol upon the stomach are to benumb its tissues, 



96 SECOND BOOK IN PHYSIOLOGY. 

impair the gastric juice, cause dyspepsia, inflammation, catarrh, ulcer- 
ation, and cancer. Four ounces of claret lessened digestion one-half. 

8. Alcohol causes hardening and fatty degeneration of the liver. 

9. Alcohol does not support assimilation, heat, or force production, 
and hence is not a food. 

10. Alcohol lessens heat and force. 

11. The use of alcoholic drinks engenders an artificial craving which 
nothing else will satisfy, and leads to drunkenness. - 

12. Many of the worst effects of alcohol may be seen in moderate 
drinkers. 

13. Life-insurance records show that alcohol shortens life, even 
when used moderately. 

14. "Bitters" nearly always contain alcohol, sometimes in larger 
proportion than does rum or w-hiskey. Their habitual use occasions 
even worse effects than the use of ordinary liquors. 

15. The first tobacco-users were the American Indians. 

16. Tobacco contains a deadly poison, nicotine. 

17. Dyspepsia, sore throat, and cancer of the throat or lip result 
from tobacco- using. 

18. Tea and coffee are not foods : they contain poisonous principles. 
theine and caffeine. Their use is a common cause of indigestion. 

19. Chloral, opium, and other narcotics, when habitually used, de- 
range the digestive organs, and produce the " poison-habit." 

20. Persons who become addicted to the use of one narcotic, are also 
likely to indulge in others. 



CHAPTER XI. 

THE BLOOD. 

108. We have already learned that one of the essen- 
tial processes in the nutrition of the body is the circula- 
tion. It is by means of the circulation that worn-out 
particles are removed from the tissues and carried to 
the organs which expel them from the body, while new 
material is distributed to the tissues, to repair the losses 
sustained in doing vital work. The medium through 
which this process is carried on is the blood. The blood 
is a red, opaque, viscid fluid, somewhat heavier than wa- 
ter, and is found in nearly every part of the body. The 
quantity of blood in the body generally equals about one 
thirteenth of its w r eight. Thus, a person weighing one 
hundred and thirty pounds has about ten pounds of 
blood. 

169. Composition of the Blood. — When examined 
with a microscope (see Experiment 9, page 272) the blood 
is found to be made up of a clear fluid, the plasma, in 
which are suspended myriads of little bodies termed 
blood corpuscles. (See frontispiece.) The corpuscles con- 
stitute about one-half of the entire bulk of the blood. 
They are so very small that more than a million have 
been counted in a single drop of blood. The number of 
corpuscles is diminished by fasting and by loss of sleep. 

170. The Blood Corpuscles. — A careful micro- 
scopic examination of the blood discloses two kinds of 

5 



98 



SECOND BOOK IN PHYSIOLOGY. 



corpuscles, known respectively as white and red corpus- 
cles. There are three white corpuscles to one thousand 
red ones. The white cells are spherical in form, and 
measure about 2-3V0 °f an ^ uc ^ ^ n diameter. The white 
corpuscles are formed by the spleen, the lymph glands, 
and the bone marrow. 

171. The Red Corpuscles. — In form, the red cor- 
puscles are very unlike the white, as will be seen by ref- 
erence to the cut. Their 
outline is that of a flat- 
tened disk g-gVa- of an 
inch in its greatest di- 
ameter. Each face is 
hollowed out in the cen- 
tre, so that the corpus- 
cle is biconcave. The 
red corpuscles are some- 
what smaller than the 
w r hite ones, and are of a 
light amber color when 
seen through the mi- 
croscope. The red cor- 
puscles are formed by 

the red marrow of the bones. 

172. The Plasma. — The plasma, a clear, colorless 
fluid, in which the corpuscles float, somewhat resembles 
ihe white of an egg diluted so as to be nearly as thin as 
water. It is chiefly made up of the various constituents 
of the digested food. In addition to these useful ele- 
ments, the plasma contains in solution the waste sub- 
stances which are to be removed from the body by 
the lungs, kidneys, skin, and other organs of excretion, 
including the gases, carbonic acid and oxygen. The 
blood contains something for every tissue : the brain, 




Fig. 14. — Red Blood Corpuscles. 



THE BLOOD. 99 

nerves, muscles, bones, glands, membranes — all are pro- 
vided for. 

173. The Spleen. — This remarkable organ is locat- 
ed at the upper and left side of the abdominal cavity, 
near the lower border of the ribs. It is of a dark purple 
color, and is about the size of one's fist. It is believed 
that its chief use is to make white blood corpuscles, and 
to destroy red ones. 

174. Uses of the Blood. — The blood is the me- 
dium of exchange between the different parts of the 
body. It has been aptly called a " circulating market," 
from which each tissue takes something, and to which 
each gives something in exchange. Some organs take 
from the blood more than they give back to it ; others 
give more than they receive. To the nerves, muscles, 
bones, and other tissues, the blood supplies the elements 
which they require to make good their losses from vital 
work, and receives in return the worn-out particles 
which must be carried away for use elsewhere, or for 
removal from the body. 

In the lungs the blood yields up the carbonic acid gas 
which it has gathered from the tissues, in exchange for 
oxygen which it returns to them. The skin, the kidneys, 
and other climinative organs, take from the blood water 
and waste particles, giving nothing in return ; but this 
uneven exchange is compensated for by one of an oppo- 
site kind. The walls of the alimentary canal absorb the 
digested food, and thus bring to the blood a large sup- 
ply of new material, in exchange for which the blood 
gives only the comparatively small amount of nutrient 
substance needed to keep in repair the digestive organs 
and manufacture the digestive fluids. 

175. The Use of the Red Blood Corpuscles. — 



100 SECOND BOOK IN PHYSIOLOGY. 

These wonderful little bodies perform a very important 
office in the body. They possess the remarkable proper- 
ty of being able to absorb and carry a volume of oxy- 
gen or carbonic acid gas much greater than themselves. 
While exposed to the air in the lungs, each corpuscle 
takes up a load of oxygen and carries it to the tissues, 
where the oxygen is given up, and an equal amount of 
carbonic acid gas is absorbed and carried to the lungs, 
and exchanged for oxygen. The color of the blood is 
due to the red blood corpuscles. It is bright red when 
the corpuscles are loaded with oxygen, but of a darker 
color when the oxygen has been exchanged for carbonic 
acid gas. 

176. Use of the White Blood Corpuscles.— The 
white blood corpuscles assist in the repair of injuries 
to the tissues. They are always found in great numbers 
in a part which is inflamed. 

Recent observations seem to show that one of the 
most important uses of the white blood corpuscles is 
to destroy germs and other noxious foreign substances 
which may find their way into the blood. This is 
perhaps their most important function. In the air we 
breathe, and in food and drink, we are constantly tak- 
ing in great numbers of germs. The multiplication of 
these minute forms of life within the body would result 
in speedy death were there not some means of destroy- 
ing them. In health, the white corpuscles constitute 
a vigilant body-guard, by which these intruders are 
promptly seized and destroyed, unless they enter the 
body in such numbers as to overwhelm the corpuscles. 
If, from any cause, the white corpuscles are so weaken- 
ed that they cannot perform their duty, the body falls 
an easy prey to these most dangerous of all enemies to 



THE BLOOD. 1.01 

human life. It is also probable that the corpuscles are 
useful in liquefying for removal the hard masses often 
left behind bv inflammations. It is, then, of the utmost 
importance that our blood corpuscles should be pre- 
served in the most perfect health, and that we should 
avoid the use of any substance which will interfere with 
their useful work, such as alcohol or tobacco, and other 
narcotics. 

Scientific research has recently brought to light the 
remarkable fact that the fluid portion, or serum, of the 
blood also possesses the ability to destroy germs. This 
power is lost, however, when the blood is rendered im- 
pure by gross food, and especially by taking into the 
system such poisons as tobacco, opium, alcohol, and other 
narcotic drugs. This is one reason why beer-drinkers 
frequently die from comparatively slight injuries, and 
why drunkards are the first victims in cholera and 
yellow-fever epidemics. 

SUMMARY. 

1. The circulation of the blood is one of the most essential pro- 
cesses of nutrition. 

2. The blood is composed of plasma and red and white corpuscles. 

3. Red corpuscles cany oxygen and carbonic acid gas ; white cor- 
puscles repair tissues and destroy germs. 

4. The blood may be compared to a circulating market. 

5. The serum of the blood, when pure, possesses the power to de- 
stroy germs. This is lost when the blood becomes impure. 



CHAPTER XII. 
THE HEART, BLOOD-VESSELS, AND LYMPHATICS. 

177. The chief means by which the blood is circulat- 
ed are the heart and a system of closed tubes connected 
with it — the blood-vessels. (See frontispiece.) The lat- 
ter are of three kinds : the arteries, which conve}^ blood 
from the heart to the tissues ; the veins, which return 
blood from the tissues to the heart ; and the capillaries, 
very fine vessels which unite the ends of the arteries 
and the veins. 

178. Structure of the Heart. — The heart may 
be described as a hollow muscle. Its size in any indi- 
vidual is that of his own fist. Its shape is conical. It 
is suspended in the chest, with its base upward, and is 
placed between the two lungs, which fold around the 
organ so as nearly to cover it. It is placed about mid- 
way between the upper and lower borders of the chest, 
and a little to the left of the median line. The heart 
is enclosed in a sac — the heart-case or pericardium — in 
which it moves easily, as the surfaces of the sac are kept 
well lubricated by a limpid, watery secretion. The walls 
of the heart are composed of muscular fibres, closely 
interwoven. 

179. The Cavities of the Heart. — A perpen- 
dicular muscular partition divides the heart into a right 
and a left half, each of which is again divided by a 
membranous cross -partition into an upper and a lower 



THE HEART, BLOOD-VESSELS, AM) LYMPHATICS. L03 



portion, making four cavities in all. (See page 104.) 
The heart may be properly regarded as a double organ, 
each lateral half being really distinct in function, and 
having an upper and a 
lower cavity. The cav- 
ities of the heart are 
lined by a delicate mem- 
bra ne similar to that 
which lines other closed 
cavities in the body. 

ISO.TheAuricles.- 
The two upper cavities 
of the heart are known 
as auricles — right and 
left respectively. Their 
walls are comparative- 
ly thin, containing but 
little muscular tissue. 
Each cavity is capable 
of holding about six 
ounces of blood. 

181. The Ventricles. 
— The two lower cavi- 
ties of the heart are 

called ventricles — the right and the left ventricle. The 
Avails of the ventricles are very much thicker than 
those of the auricles, and the wall of the left ventricle 
is much thicker than that of the right. The two cav- 
ities are of the same size, and capable of holding about 
six' ounces each. 

182. Openings into the Heart. — Each ventricle 
has two openings, one leading to the auricle of the same 
side, the other connected with an artery. The right 




Fig. 15. — The Heart. 



104 



SECOND BOOK IN PHYSIOLOGY. 




ventricle communicates with the pulmonary artery, 
which goes to the lungs; the left, with the aorta, the 
largest artery of the body. 

The right auricle presents two openings in its outer 
wall, through which it receives blood from the two larg- 
est veins in the bod\^, the ascending and the descending 
vena cava. The left auricle has four openings, which 
receive the blood from the four pulmonary veins, two 
from each lung. 

183. The Valves of the Heart. — The two open- 
ings of each ventricle are guarded by valves, which per- 
mit the blood to pass in but one direction. The valve 

between the right auricle and 
the right ventricle consists of 
three delicate membranous cur- 
tains. One side of each curtain 
is attached to the edge of the 
opening, while the other is at- 
tached by tendinous cords to 
the walls of the ventricle. The 
valve between the left auricle 
and the left ventricle has two 
Fig. 16.— Inside of Heart, such curtains. As the ventricles 
fill with blood, these curtains 
float up until they completely close the openings be- 
tween the ventricles and the auricles. The valve of 
the right side is known as the tricuspid valve ; that of 
the left side, as the bicuspid or mitral valve. The open- 
ing from the left ventricle into the aorta, and that of 
the right ventricle into the pulmonary artery, are 
guarded by the aortic and pulmonary valves, exactly 



THE HEART, BLOOD-VESSELS, AND LYMPHATICS. 105 

alike, and known as the semilunar valves. These 
valves allow the blood to pass from the auricles to the 
ventricles, and from the ventricles into the arteries, but 
not in the opposite direction. 

184. The Arteries. — All vessels which convey 
blood from the heart are called arteries. The largest 
artery of the body, the aorta, leaves the heart at the 
left ventricle, and soon begins to send off branches to 
various parts. These branches subdivide many times, 
until they become exceedingly minute, quite too small 
to be seen by the naked eye. 

185. The Capillaries. — The smallest divisions of 
the arteries terminate in a net -work of very small 
vessels, which are termed capillaries. An idea of the 
relation of the arteries to the capillaries may be ob- 
tained by observing the veins of a neWeined leaf. It 
will be noticed that the veins of the leaf continually 
subdivide until they end in a delicate net-work which 
resembles the finest lace. This is well shown in a 
u skeleton leaf." 

186. The Veins. — The capillary vessels are very 
short. They soon begin to gather into larger and larger 
trunks, thus forming the veins. The veins unite as they 
approach the heart, forming larger and larger trunks, un- 
til at last two large veins are formed, one coming from 
the upper part of the body, the other from the lower 
part, known respectively as the descending vena cava 
and the ascending vena cava. 

187. Structure of the Blood-vessels. —The large 
arteries have firm, elastic walls, which retain their form 
whether full or empty. The walls of the arteries are made 
up of three layers : a lining of membrane, a covering of 
connective tissue, and a middle layer of muscular tissue. 

5* 



106 



SECOND BOOK IN PHYSIOLOGY. 



In the smallest arteries, the outer layer becomes very 
thin, and the muscular layer much thicker. In the cap- 
illaries the muscular coat is lost, the walls consisting of 
membrane only, and being so thin as to be transparent. 
The smallest capillaries are hardly so large in diameter 
as the red corpuscles. The veins have thinner and less 
rigid walls than the arteries, with verv thin muscular 
fibres. In many parts of the body they are furnished 

with valves, which are not found 
in the arteries. The valves of 
the veins act in such a manner 
as to allow the blood to pass in 
but one direction, towards the 
heart. 

188. Capacity of the Blood- 
vessels. — The blood-vessels are 
capable of holding much more 
blood than they are ever re- 
quired to contain. The veins 
have a capacity more than dou- 
ble that of the arteries, and suf- 
ficient to contain all the blood 
of the body. 

189. The Systemic Circula- 
tion. — When the blood leaves 
the left ventricle it is distrib- 
uted through the arteries to the capillaries in all parts 
of the body, whence it is gathered up by the veins and 
brought back to the heart. The blood sent out by the 
left ventricle reaches the heart again at the right auricle, 
from which it enters the right ventricle. This course of 
the blood from the left ventricle to the right ventricle is 
known as the systemic circulation. (See frontispiece.) 




17. — Valves of Veins. 



ARTERIES PULMONARY CI RCULATIONM VEINS 



RIGHT HEART 



* 




\ <*^ V 

P ORTALVE,N ^ * '**9 



DIAGRAM OF THE CIRCULATORY SYSTEMS. 



106— A. 



Plate IV. 



THE HEART, BLOOD-VESSELS, AND LYMPHATICS. 107 

190. The Pulmonary Circulation. — The blood 
which is sent out by the right ventricle is carried by the 
pulmonary artery to the lungs, whence it is collected and 
carried to the left auricle by the four pulmonary veins. 
From the left auricle the blood passes to the left ventri- 
cle. This course of the blood from the right ventricle 
through the lungs to the left ventricle is known as the 
p almonary circulation. 

191- The Portal Circulation. — Some of the blood 
which leaves the left ventricle in its course through the 
systemic circulation does not return directly from the 
capillaries to the heart. That portion which is distrib- 
uted to the stomach, spleen, pancreas, and intestines is 
gathered up into a single large vein, the portal vein, by 
which it is taken to the liver, where it is again spread 
out in a capillary system. This blood is distributed in 
the capillaries of the liver, and at length finds its way 
back to the systemic circulation through the hepatic 
vein, thus passing through two sets of capillaries in its 
course from the left to the right side of the heart. This 
is known as the portal circulation. (See Plate I.) 

192. The Lymphatic System. — Closely connected 
with those portions of the circulatory apparatus already 
described is the lymphatic system, which comprises the 
lymph-vessels, or lymphatics, the lymphatic glands, and a 
circulating fluid, the lymph. 

193. The Lymph-vessels. — Outside the blood-vessels 
in the interlacing net-work of the tissues are numerous 
irregular spaces filled with fluid. Connected with these 
spaces are minute tubes, the lymphatics, or lymph-ves- 
sels, which form an intricate net-work throughout the 
body, all converging towards the centre of the trunk, 
where they unite to form two large vessels, or ducts, 



108 



SECOJSTD BOOK IN PHYSIOLOGY. 



which join the venous circulation near the heart. One 
which passes upward along the back side of the abdo- 
men and joins the large vein from the left arm, is known 
as the thoracic duct, which, as we have elsewhere learn- 
ed, carries some portion of the digested food as well as 
lymph. The lacteals is the name given to the lymph- 
vessels of the intestines. The lymph-vessels are abun- 
dantly supplied with valves, which allow the lymph to 
flow only in the direction of the heart. 

194. The Lymphatic Glands. — Scattered 
here and there throughout the body are found 
roundish masses of varying size, through which 
the lymph-channels pass in their progress to- 
wards the heart. These are called lymphatic 
glands. The largest collections of lymphatic 
glands are found in the neck, the axilla, and 
the groins. Large numbers of these glands 
are placed along the intestinal canal, being 
here termed the mesenteric glands. 

195. The Lymph. — The spaces in the tis- 
sues and the lymphatic vessels connected with 
them contain a clear, colorless fluid, the lymph, 
which closely resembles the blood, only it is 
not red in color, and contains great numbers 
of white blood corpuscles, with but few red 
ones. The lymph is chiefly derived from the 
capillaries and minute blood-vessels, the thin 
walls of which allow the plasma to soak 

through into the tissue spaces. Many of the white 
blood corpuscles, with a few red ones, also manage 
to escape through the capillary walls into the tissue 
spaces. 

The lymph receives nutritive elements, — digested food, 



Fig. 18. 
Lymphatic 

Vessel. 



THE HEART, BLOOD -VESSELS, AND LYMPHATICS. 109 



water, and oxygen from the 
blood, — and conveys them to 
the tissues. These, in turn, give 
up to the lymph their waste ele- 
ments, which are passed from 
the lymph to the blood. The 
lymph thus forms a medium of 
exchange between the blood and 
the tissues. 

It is thus readily seen that 
the lymphatic system is an im- 
portant part of the general cir- 
culatory system. It not only 
serves as a medium of exchange 
between the blood and the tis- 
sues, but returns to the heart 
those portions of the blood which 
escape from the blood-vessels 
into the tissues, and drains the 
tissues of superfluous fluid, waste 
matters, and worn-out elements. 

The lymph-vessels also drain serous cavities, such as 
joints, the heart -case, and the cavity of the chest, be- 
ginning in these structures by means of small openings 
in the lining membrane. 

The lymphatic glands contain cells resembling the 
white blood corpuscles, which multiply by division, thus 
adding to the number of white corpuscles in the body. 
It is a curious fact that the older white blood corpuscles 
are broken up and disappear in the lymph-glands, their 
remains being taken up by the newly formed white 
corpuscles just as are germs and other foreign particles 
which sometimes enter the blood. 




Fig. 19. 
Lymph- gland and Vkssels. 



HO SECOND BOOK IN PHYSIOLOGY. 

SUMMARY. 

1. The heart and the blood-vessels are the chief means by which the 
blood is circulated. 

2. The heart is a hollow, muscular organ, really a double organ, 
each half having two cavities — auricle and ventricle — and two sets of 
valves. 

3. Arteries convey blood from the heart ; veins convey blood to the 
heart ; capillaries connect arteries and veins. 

4. The arteries and the veins have three coats — outer, inner, and 
middle. The middle coat is muscular. The capillaries have only the 
lining coat. The veins have valves. 

5. There are three circulatory systems : Left side of heart to right 
side — systemic; right side to left — pulmonary ; from stomach, intes- 
tines, pancreas, and spleen, through the liver — portal. 

6. In the general circulation there are two sets of vessels which re- 
turn blood to the heart, viz., the veins and the lymph- vessels. 

7. The lymph-vessels collect from spaces in the tissues the clear 
fluid, the lymph, which they empty into the large veins near the 
heart. 

8. The lymph is chiefly made up of white blood corpuscles and 
blood plasma. 

9. The lymph-vessels are connected with the lymphatic glands. 

10. The lymph forms a medium of exchange between the blood and 
the tissues, returns to the blood escaped corpuscles and plasma, and 
removes from the tissues surplus fluid and waste and worn - out 
elements. 

11. The lymph- vessels and glands connected with the intestines are 
called lacteals and mesenteric glands. 

12. The lymphatic glands destroy old white-blood corpuscles, and 
form new ones. 



CHAPTER XIII. 
HOW THE BLOOD IS CIRCULATED. 

196. The circulatory system of the body comprises the 
heart, blood, blood-vessels, lymph, lymph - vessels, and 
lymphatic glands. The heart is the great centre of the 
circulatory apparatus. It may be called a self-operating 
force-pump, which, alternately filling and emptying it- 
self, keeps up the circulation of the blood throughout the 
body, from earliest infancy to the latest moment of life. 

197. The Heart-beat. — If the hand is placed just 
over the fifth and sixth ribs, a little to the left of the 
breastbone, an impulse will be felt with each beat of 
the heart. After each impulse will be observed a short 
pause, lasting about as long as the beat. This fact ac- 
counts for the ability of the heart to work so incessantly. 
It takes a short rest after each beat. 

198. Work Done by the Heart. — The amount of 
work done by the heart during life, or even during a 
single day, is immense. At each beat the ventricles lift 
into the arteries about twelve ounces of blood. In less 
than half a minute, at the usual rate of beating, an 
amount of blood passes through the heart which is equal 
to the entire quantity of blood in the body. In twenty- 
four hours the blood pumped by the heart amounts to 
the enormous quantity of more than three hundred bar- 
rels. The force required to circulate this amount of 
blood is estimated to be not less than that which would 



112 SECOND BOOK IN PHYSIOLOGY. 

be used in lifting one hundred tons one foot high in a 
minute. 

199. The Heart-sounds. — By placing the ear to 
the chest of another person, one may hear at the mo- 
ment of the heart - beat a peculiar sound. By giving 
very careful attention, two sounds may be heard. The 
sounds of the heart are chiefly caused by the closure of 
its valves. 

200. Heart Regulators. — The heart is supplied 
with two very important nerves which regulate its ac- 
tion. One of these nerves causes the heart to go faster, 
when greater activity is required, and the other causes 
it to beat slower, when it tends to go too fast. Thus, 
by the combined action of these two nerves, the heart's 
action is regulated to a nicety. 

201. The Pulse. — In the arteries the blood travels 
in waves or jets. At some points large arteries come near 
to the surface of the body, and if the finger is placed 
upon one of these points an impulse can be felt at each 
beat of the heart, which is called the pulse. We usually 
feel the pulse at the wrist ; but it may be felt at the 
neck and many other places. If we count the pulse of 
a child, we find it beating at the rate of eighty to one 
hundred a minute. In grown persons, the rate is sixty 
to seventy beats a minute. The pulse-rate changes also 
with exercise and change of position. A record of the 
pulse may be made by means of an ingenious instru- 
ment called a sphygmograph, or pulse-writer. The rec- 
ord made by a healthy person is shown on page 121, 
where it is compared with the record made by the pulse 
of a drunkard and by that of a tobacco-user. By the use 
of this instrument it is easy to tell whether a person has 
a weak or a strong heart. (See Experiment 10, page 273.) 



TIOW THE BLOOD IS CIRCULATED. 113 

202, The Capillary Circulation. — By the aid of 

a good microscope the circulation of the blood may be 
easily studied in the thin web of a frog's foot. (See 
frontispiece.) The red corpuscles may be seen filing 
slowly through the narrow capillaries, sometimes singly, 
often in ranks of two or three, until they reach the small- 
est capillaries, through which they pass in single file. A 
minute inspection shows here and there a white corpus- 
cle, apparently clinging to the wall of the blood-vessel, 
or dragging itself slowly along in the direction of the 
current. Occasionally one will be found which is mak- 
ing its way in some mysterious manner through the 
vessel wall. After performing in the tissues some duty 
too subtle for the eye to follow, the white corpuscle 
which has escaped starts off on its journey back to 
the heart by the roundabout road of the lymph-ves- 
sels. 

It is in the capillary circulation that the exchanges 
between the blood and the tissues take place. 

203. The Circulation in the Veins and the 
Lymph-vessels. — The blood flows onward in the veins 
in a steady stream. The valves with which the veins are 
provided prevent any backward movement of the blood, 
and the pressure from behind constantly urges it for- 
ward. The expansion of the chest with each act of in- 
spiration produces a suction force which empties the 
large veins near the heart. The ventricles of the heart 
act slightly in the same manner, as they expand after 
each contraction. This suction action of the heart and 
the chest, especially of the latter, assists the lymphatic 
circulation as well as the movement of the blood in the 
veins. The action of the chest is also especially use- 
ful in aiding the portal circulation. 



114 SECOND BOOK IN PHYSIOLOGY. 

204. Venous and Arterial Blood. — The blood which 
circulates in the arteries of the systemic circulation, 
called arterial Mood, is bright red in color. During its 
passage through the capillaries of the systemic circula- 
tion the blood, as we have already seen, gives up its oxy- 
gen in exchange for carbonic acid gas, which occasions a 
change in color from bright red to dark purple. It is now 
known as venous blood, and must be distributed to the 
various eliminative organs for purification. The pulmo- 
nary arteries, receiving their blood from the right side 
of the heart, contain venous blood ; while the pulmonary 
veins, receiving the blood after it has passed through the 
lungs, contain arterial blood. 

205. Regulation of the Blood Supply. — The gen- 
eral supply of blood to the body is regulated by the 
action of the heart. When more blood is needed by 
the tissues in general, as in active exercise, the heart 
works faster ; and when less is required, as during rest 
or sleep, its rate is diminished. Each part of the body 
requires, in addition, some special means for regulat- 
ing its blood supply. This special regulation is secured 
through nerves connected with the muscular coats of the 
arteries. (See Experiments 11, 12, pages 273, 274.) When 
more blood is needed in a certain organ or part, the 
muscular coats of the small vessels are, through the in- 
fluence of certain nerves, caused to relax, so that the 
blood passes through more rapidly, and a larger supply 
is thus obtained. When less blood is wanted, the ves- 
sels are made to contract, and thus the amount of blood 
received is diminished. Blushing is due to a sudden re- 
laxation of the vessels of the face under the influence of 
certain mental emotions. The same effect is produced 
by alcohol and some other drugs. Blanching of the 



IIOW THE BLOOD IS CIRCULATED. 115 

face, or pallor, results from sudden contractions of the 
small vessels, the effect of fear, rage, or distress. 

The heart seems to be constantly active, but this is 
not really the case. As a matter of fact, the heart oc- 
cupies nearly as much time in resting as in working. 
Each contraction occupies nearly half a second, and each 
beat is followed by a complete rest of about half a sec- 
ond. It is this constant stopping to rest that enables 
the heart to work on during a long life, apparently 
without stopping to rest. 

SUMMARY. 

1. The circulatory apparatus comprises the heart, blood, blood-ves- 
sels, lymph, lymph-vessels, lymphatic glands. 

2. The pulse is the impulse felt in an artery. The average pulse-rate 
is sixty to seventy per minute, varying with age, position of body, and 
exercise. 

3. The blood moves in the arteries with irregular impulses ; in the 
veins, in a slow, steady stream; in the capillaries the movement is al- 
most imperceptible. 

4. The general and local supply of blood is regulated by the action 
of the nervous system upon the heart and the muscular walls of the 
small arteries. 

5. The heart rests between its beats. 



CHAPTER XIV. 

HYGIENE OF THE HEAKT, BLOOD, AND BLOOD- 
VESSELS. 

206. The heart is one of the most essential of all the 
vital organs. Its sudden failure causes instant death, 
and yet it may go on beating regularly seventy or more 
times a minute, without once missing a beat, for three or 
four score years, or even for a century. Nature has pro- 
vided the most ample and efficient means for adapting 
its action to all the ordinary conditions and emergencies 
of life ; and if we take care to impose upon it no need- 
less burdens, and to subject it to no ill-treatment, we 
may expect it to do its duty well for a long lifetime. If 
it fails to do this, the cause is usually some indiscretion 
for which we are ourselves responsible. 

207. Effects of Exercise upon the Heart — When 
a person walks rapidly, or runs, or engages in any form 
of active exercise, the heart beats faster just in propor- 
tion to the degree of activity. Every one has experi- 
enced the heavy and rapid beating of the heart which is 
excited by violent exertion, as from running until out of 
breath. The heart is a muscle, and whatever calls into 

action the other muscles of the bodv causes the heart to 

«/ 

make extra exertion also. 

If a person's habits are sedentary, — in other words, if 
he does not accustom himself to daily and active exer- 
cise, — the heart, as well as the other muscles of the body, 



HYGIENE OF THE BEAitT, BLOOD, ETC. 117 

becomes weak. If such a person hurries to catch a train, 
or runs up a flight of stairs, he gets out of breath very 
easily, and perhaps suffers from a heavy beating or pal- 
pitation of the heart. Sufficient daily exercise should be 
taken to keep the heart strong and vigorous, so that it 
will not be unpleasantly affected by moderate exertion. 
A person whose heart has been well strengthened by 
systematic muscular exercise can walk rapidly for hours 
without inconvenience. 

Proper exercise also secures good distribution of the 
blood, a quickening of the assimilation in all parts of the 
body, and a more prompt and thorough removal of the 
waste elements. Violent exercise should be avoided by 
a person who has not by daily and carefully graduated 
practice become accustomed to it. 

208. Effects of Heat and Cold. — Heat stimulates 
the heart's action to a high degree. The effect of cold 
is to depress and paralyze the action of the heart and 
small blood-vessels ; hence the importance of protecting 
the body from extremes of heat and cold, by carefully 
adapting the clothing to the season and the circum- 
stances. It is particularly important to clothe well the 
extremities, so that a proper balance of the circulation 
may be maintained. 

The clothing must not obstruct the circulation. Many 
of tho largest veins, particularly those of the extremities, 
are located near the surface, so that any constriction is 
certain to interrupt the flow of blood through them. 
Tight shoes or boots, elastics for the arms or legs, and 
constrictions about the waist or neck, are all very in- 
jurious. 

209. Sleep and the Blood. — Every one has noticed 
that loss of sleep causes a person to look pale. During 



118 SECOND BOOK IN PHYSIOLOGY. 

sleep the red corpuscles which are worn out during the 
day are replaced, and thus the red color of the blood is 
maintained. If one does not sleep, this repair of the 
blood does not take place so perfectly, and the blood be- 
comes thin and pale. Pallor is also due in part to the 
exhaustion of the nervous system. 

210. Mental Influences. — Violent emotions of ev- 
ery description affect the heart injuriously. Many a 
man has dropped dead under the excitement of rage, 
through sudden failure of the heart. The receipt of joy- 
ful news has sometimes occasioned so great excitement 
of the emotions as to cause death by overtaxing the 
heart. The lesson to be learned from these facts is that 
the emotions and passions should be kept well under 
control. A violent fit of anger is really as dangerous as 
exposure to small-pox or cholera. 

211. Food and Blood. — The blood is made of what 
we eat. Poor food makes poor blood, which in turn 
makes poor tissues, and hence a poor body. An insuf- 
ficiency of food very soon makes the blood poor and 
thin. Exciting, irritating, or stimulating foods injure 
the quality of the blood, and thus cause every tissue in 
the body to suffer. Condiments, such as pepper, pepper- 
sauce, mustard, and other hot and irritating substances, 
are to be condemned on this ground. Excess in the use 
of fats and highly seasoned foods renders the blood 
gross and impure. 

212. Effects of Alcohol upon the Blood. — A 
drop of alcohol added to a drop of blood almost instant- 
ly destroys the blood corpuscles. Prof. William Car- 
penter, M.D., the eminent English scientist, asserts that 
one part of alcohol in five hundred parts of blood will 
injure the blood and the tissues. This proportion of 



HYGIENE OF THE BEART, BLOOD, ETC. 119 

alcohol is furnished by a large quantity of any strong 
liquor, or a large quantity of wine, beer, or cider. When 
alcohol is taken freely, the blood loses in part its power 
to carry oxygen. This accounts for the bluish appear- 
ance of the face, nose, and lips of a hard drinker. Alco- 
hol, even in small quantities, coagulates the fibrine of 
the blood, producing fine clots, Avhich obstruct the capil- 
laries, causing degeneration of tissues, and thus laying 
the foundation for incurable diseases. 

As we have learned, one of the most important uses 
of the white blood corpuscles is to destroy germs and to 
repair the tissues. Alcohol paralyzes these delicate ele- 
ments of the blood so that they cannot do their work 
properly. A man under the influence of alcohol is pre- 
cisely in the condition of a city whose guard of soldiers 
has been put to sleep by some powerful drug ; the en- 
emy enters without resistance. It is for this reason, no 
doubt, that drunkards are so susceptible to various germ 
diseases. Persons addicted to the use of alcohol are 
usually the first victims to cholera and yellow -fever. 
This is doubtless one reason, also, why intemperate per- 
sons do not recover from accidents or surgical operations 
as reaclilv as do total abstainers. 

213. Alcohol and Fatty Degeneration. — It is also 
found that the habitual use of alcohol increases the 
amount of fat in the blood, causing in various organs the 
change known as fatty degeneration, in which portions 
of the brain, liver, heart, kidneys, and other organs are 
changed to fat. When this change has occurred in an 
important vital organ death is a certain result, as the 
condition is incurable. 

214. Effects of Alcohol upon the Heart and the 
Blood-vessels. — Alcohol quickens the pulse, not by 



120 SECOND BOOK IN PHYSIOLOGY. 

giving strength to the heart, but by paralyzing the 
nerve centres which control the heart and the small 
blood-vessels. Benumbed by alcohol, these nerve cen- 
tres lose their control over the muscular walls of the 
small arteries, allowing them to relax; the blood is thus 
allowed to flow through them more easily, a share of 
the resistance which the heart is accustomed to over- 
come having been removed. In consequence, the heart 
" runs away," as it were, like a steam-engine which has 
lost its "governor," or a clock pendulum from which the 
weight has been removed. 

215. Alcohol and Animal Heat. — The larger 
amount of blood circulating in the small arteries of the 
surface of the body, when alcohol has been taken, pro- 
duces a sensation of increased warmth ; but the blood 
cools off so much more rapidly at the surface than in 
the interior of the body, that the general temperature 
quickly falls. The small amount of heat possibly pro- 
duced by alcohol is not sufficient to make good this ex- 
tra loss. It is thus evident that alcohol is of no value 
to the body as a source of heat. All the survivors of 
the ill-fated G-reely expedition were total abstainers. 

216. Alcoholic Disease of the Heart and the 
Blood-vessels. — A heart which has been thus abused 
by alcohol, after a time becomes weak and irregular in its 
action, as is well shown by the sphygmographic tracing 
of a drunkard's pulse, given on the next page. Compare 
this with the tracing of the pulse of a healthy person, 
shown on the same page. 

The long-continued use of alcohol in large quantities 
produces organic or structural changes in the heart. It 
sometimes becomes overloaded with fat. In other cases 
its muscular tissue is changed to fat and loses its strength, 



BYGIENE OF THE BEART, BLOOD, ETC. 121 

so that the heart-beat is a mere flutter. The muscular 
walls of the small arteries of the brain and other parts 
undergo a similar change, and finally become so weak 
that they are unable to resist the pressure of the blood. 
A rupture occurs, and the patient dies of apoplexy. 

Several years ago some very interesting experiments 
were made in England by the celebrated Dr. Parkes, 
F.R.S., who had in charge the sanitary department of 
the British army. Dr. Parkes gave alcohol to a soldier, 
and then observed his pulse. He found that one ounce 
of alcohol a day increased the heart-beats very percepti- 
bly, and that eight ounces, equivalent to a pint of whis- 
key, compelled the heart to beat one-fourth more times 
than when water only was used. In view of these facts, 
it is not surprising that those who use alcohol are so lia- 
ble to disease of this important organ. 



s 



OF IIEALTUY PERSON. 



OF TOBAOCO-DSEK. 



OF UEUNKAED. 

Fig. 20. — Sphygmographic Tracings of the Pulse. 

217. Effects of Tobacco upon the Heart and 
the Blood. — The pulse of the tobacco - user indicates 
unmistakably the injury which this drug works upon 
the heart. It has lost the firm, steady beat of 
health, and is feeble and irregular. The sphygmograph 
6 



122 SECOND BOOK IN PHYSIOLOGY. 

shows this very plainly. This condition is now so well 
known that it has received the name "tobacco heart" 
and is so called by physicians. Those who have made 
a careful study of this subject claim that not less than 
one in every four users of tobacco have this kind of 
heart. The examining surgeons of the United States 
army state that a large share of the young men who are 
rejected are found to be suffering from tobacco heart. 

B. W. Richardson, M.D., F.R.S., has made many ex- 
aminations of the blood of tobacco-users, and states that 
the effect of smoking is to make the blood thin, and to 
cause the corpuscles to lose their round form and the 
ability to adhere together, which are signs of good 
health. 

Some users of tobacco may say: u If these facts are 
true, why do not all tobacco-users die from the use of 
the weed ?" The answer to this is that the system has 
a wonderful power of adaptation ; so great, indeed, that 
one may accustom himself to the use of almost any poi- 
son until he can take it in enormous doses, and appar- 
ently without suffering immediate injury, although de- 
structive changes which w^ill ultimately result in death 
may be slowly taking place all the time. If it were not 
for this fact, many tobacco-users would not live twenty- 
four hours. It is doubtless the case, nevertheless, that 
most persons who habitually use tobacco actually die of 
its use, since their lives are shortened, or their systems 
prepared for the ready reception of some disease which 
carries them off prematurely. 

No boy or young man can afford to acquire the prac- 
tice of using this filthy weed. Its effects upon adults 
are bad enough, but upon boys and young men its influ- 
ence is even worse. 



HYGIENE OF THE HEART, BLOOD, ETC. 123 

21S. Tea and Coffee. — Palpitation, or heavy beat- 
ing* or thumping of the heart, is an unpleasant symptom 
with which almost every one is familiar. Those who 
are addicted to the use of strong tea and coffee often 
suffer from this annoying affection. These beverages 
are very unwholesome, especially for young persons, and 
may be well replaced by so wholesome and palatable an 
article as hot milk. 

219. Fainting. — When the heart beats so feebly that 
an insufficient quantity of blood is sent to the brain, 
the person becomes unconscious, or faints. A fainting 
person should be placed at once in a horizontal position, 
or with the head lower than the rest of the body. A 
little cold water should be dashed in the face or on the 
chest, and the limbs should be briskly rubbed. Hot 
water applied to the top or back of the head, or over 
the heart, is more effective than cold water. If a per- 
son faints in a close or crowded room he should be car- 
ried at once to the open air, or to a room where an 
abundance of fresh air can be secured. If nothing is 
done, the heart's action may cease entirely and death 
may occur. A fainting person is always pale. If the 
face is red, the case is probably one of apoplexy, and 
the head should be held high instead of being lowered. 
Cold water should be applied freely to the head and the 
neck, and a physician should be called at once. If the 
insensibility is caused by intoxication, the breath will 
smell of alcohol. 

220. Taking Cold. — Most colds are contracted by 
wetting the feet, getting chilled, cooling off suddenly 
when perspiring freely, or in some other way disturbing 
the surface circulation. The consequence is congestion 
of some internal organ, especially of the lungs, the.throat, 



124 SECOND BOOK IN PHYSIOLOGY. 

or the nasal cavity. When one has been exposed to the 
causes of cold, the balance of the circulation should be 
restored as speedily as possible. If one's clothing has 
been accidentally wet, and the wet garments cannot be 
exchanged at once for dry ones, he should be warmly 
wrapped up in dry blankets, or should exercise actively 
to keep up a good circulation, and thus prevent chilling. 

221. Hemorrhage. — In attempting to check severe 
bleeding from a cut or other wound, it should be remem- 
bered that the blood in an artery is flowing from the 
heart, while that in a vein is flowing towards the heart. 
Hence, in case the bleeding is from an artery, the com- 
pression by means of the thumb, the fingers, or a band- 
age should be applied on the side towards the heart. In 
case of bleeding from a vein, it should be applied on the 
opposite side of the wound. In many cases it is neces- 
sary to apply the compression upon both sides of the 
wound, as both arteries and veins may be wounded. 
Bleeding from an artery may at once be detected by 
the bright red color of the blood, and by its flowing 
in jets ; while from veins it comes in a steady stream, 
and is of a dark red color. 

If the hemorrhage is from a vein, elevate the limb 
at once. This will control a mild hemorrhage in many 
cases. If the bleeding continues, tie a marble or a large 
pebble in a handkerchief, and placing the knot upon the 
limb just above the wound, tie the handkerchief rather 
loosely around the limb. Slip a short stout stick through 
the loop, and twist it until the firm compression controls 
the bleeding. Care should be taken not to make more 
pressure than is really necessary, and the bandage must 
not be kept in position so long as to injure the parts 
by pressure. Elevation of the arms above the head, 



HYGIENE OF THE HEART, BLOOD, ETC. 125 

and bathing the face with hot water, are excellent 
means of checking nosebleed. Call a physician at once 
if the bleeding is severe and does not cease quickly. 

SUMMARY. 

1. Proper exercise increases the strength of the heart. Violent 
exercise is injurious, and may prove fatal to a person of sedentary 
habits. 

2. Heat stimulates the heart and the blood-vessels. Cold depresses 
and paralyzes. Hence the need of suitable clothing. 

3. Violent emotions affect the heart profoundly. 

4. The quality of the blood is directly dependent on the character of 
the food. 

5. Strong alcohol destroys blood corpuscles instantly. In the body 
alcohol paralyzes the blood corpuscles so that the red corpuscles can- 
not carry oxygen, and the white cannot destroy germs nor repair the 
tissues. 

6. Alcohol tends to and often causes fatty degeneration of the heart 
and other organs. 

7. Alcohol paralyzes the heart and the blood-vessels, and causes loss 
of animal heat. 

8. Tobacco often causes a diseased condition known as ''tobacco 
heart." 

9. The use of strong tea and coffee causes palpitation of the heart. 

10. Fainting is due to a sudden failure of the heart. 

11. Stop hemorrhage by compressing the wound and elevating the 
wounded part. 



CHAPTER XV. 



THE ORGAN'S OF RESPIRATION. 



222. All living things breathe. Plants breathe by 
means of their bark and leaves. The smallest insect is 
as dependent upon the " breath of life " for its existence 
as is a horse or a man. Even the smallest living cell 
breathes. The earthworm breathes with its slime-cov- 
ered skin, as it slowly wedges its way through the moist 
earth. In man and all higher animals a complicated 
mechanism is required to carry on this important vital 

process. The organs of respi- 
ration are the air-passages and 
the lungs, and the thorax, or 
chest, with its ribs and muscles. 
223. The Air-passages. — 
The passages which lead to the 
lungs begin with the mouth and 
the nostrils. The nostrils com- 
municate with the cavity of 
the nose, or nasal cavity. Be- 
ginning at the nostrils, and 
extending about one half its 
length, the nasal cavity is di- 

Fig.2L— The Upper Air-passages. v ided into two Compartments 

by a partition termed the sep- 
tum. The sides of the nasal cavity are covered with 
mucous membrane, the extent of which is greatly in- 




THE ORGANS OF RESPIRATION. L27 

creased by scroll-like projections of bone and cartilage 

from the outer walls of the cavity. 

224. The Pharynx. —The nasal cavity and the cav- 
ity of the mouth unite at their back parts to form the 
pharynx, which is separated from the mouth by a pen- 
dulous partition — the soft palate — from the centre of 
which hangs the uvula. This membranous curtain may 
be drawn up so as to close the opening between the 
pharynx and the nasal cavity. AYhen drawn forward it 
may be made to meet the tongue in such a manner as 
to separate the mouth from the pharynx. 

On either side of the pharynx are placed the tonsils, 
two glands which help form the saliva, and which are 
very apt to become acutely inflamed and permanently 
enlarged. Out of sight, behind the soft palate, on the 
back walls of the pharynx, is another gland known as 
the pharyngeal tonsil, which sometimes becomes enlarged 
and obstructs the breathing. 

225. The Larynx. — Beginning at the pharnyx is a 
cartilaginous tube leading to the lungs, the upper part 
of which is known as the larynx. This organ may be 
roughly described as a cartilaginous box containing the 
essential organs of the voice, the vocal cords, of which 
we shall learn more elsewhere. 

The upper part of the larynx is guarded by a closely 
fitting cover, the epiglottis, consisting of a leaf -shaped 
cartilage, one side of which is hinged at the root of the 
tongue in such a manner that when the tongue is drawn 
back, in the act of swallowing, the cover is tightly closed, 
preventing the entrance of food or drink into the larynx. 

226. The Trachea. — From the larynx the tube ex- 
tends down into the chest. Here it is known as the 
windpipe, or trachea, which is made up of incomplete 



128 



SECOND BOOK IN PHYSIOLOGY. 



rings of cartilage, joined together by membranes and 
other structures in such a way as to leave the back side 
of the tube closed only by soft tissues — an important 
provision, as the gullet, or meat-pipe, lies just behind the 
trachea. 

227. The Bronchial Tubes. — In the upper part of 
the chest the trachea divides into two branches, the 




Fig. 22. — Air-tubes and Air-cells 



"bronchial tubes, one of which passes off to the right side, 
the other to the left. These branches divide and sub- 
divide like the branches of a tree, to which the trachea 



THE ORGANS OF RESPIRATION. 



129 



and its branches may be not inaptly compared, viewing 
the tree inverted. 

The smallest tubes are exceedingly minute. The large 
tubes, like the trachea, have a framework of cartilagi- 
nous rings, which is covered and lined by membranes. 
In the smaller tubes the cartilage rings become less dis- 
tinct, and in the smallest are lost altogether. The walls 
of the small tubes are chiefly made up of mucous mem- 
brane and muscular tissue. 

228. The Air-cells. — At the end of each of the 
smallest air-tubes is a small sac called a lobule, which, 
by the infolding of its walls, is divided into numerous 
cells, each lobule having fifteen or twenty such subdi- 
visions. The total number of these 

air-cells in the lungs is estimated to 
be not less than 1,700,000,000. 

229. The Mucous Membrane. 
— The mucous membrane lining 
the air-tubes and cells of the lungs 
is a very remarkable structure. In 
the air-passages the membrane is 
protected by peculiar cells, which 
by the aid of the microscope are 
seen to be covered with what look 
like minute hairs. By the constant 
movement of these hairs a stream 
of mucus is kept constantly flow- 
ing upward towards the mouth, 
bringing with it particles of dust which may have been 
taken in with the breath. In the air-cells the lining 
membrane is of such marvellous thinness that two 
thousand five hundred layers would make but an inch 
in thickness. On account of the immense number of 

6* 




Fig. 23. — Lobule of Lung. 
a, Bronchiole ; c, Air-cell. 



130 SECOND BOOK IN PHYSIOLOGY. 

air-cells and minute air-tubes, the extent of this mem- 
brane is so great that if spread over a flat surface it 
would cover a space of not less than two thousand 
square feet. 

Immediately underneath this delicate membrane, in 
the walls of the air-cells, is to be found the most remark- 
able net-w T ork of capillaries in the body. The purpose 
of this extensive capillary system is to expose to the air, 
in the most thorough manner possible, all the blood that 
passes through the lungs. 

Covering the entire surface of the mucous membrane 
and lining the air-cells of the lungs, is a layer of cells 
which are capable of capturing and destroying the germs 
of various sorts w T hich are taken in with the breath. 
In cities, the air contains vast multitudes of germs, 
which float in the form of fine dust. This living barri- 
cade protects the body like a line of faithful and ever- 
active sentinels. A " cold " weakens these cells, so that 
the body is thereby rendered less able to defend itself 
against the attacks of the disease germs which are re- 
ceived through the air. This is the reason why a cold 
is so often the introduction to pneumonia or some other 
germ disease. 

Alcohol is one of the most efficient means of weaken- 
ing the lungs, as it invariably causes congestion of these 
organs, and paralyzes the protecting cells. 

Tobacco-smoke is also a most certain means of lessen- 
ing the ability of the lungs to defend themselves against 
these most deadly enemies of life and health. 

230. The Pleura. — The air-cells and the air -tubes 
are all bound together by means of connective tissue, in 
which there is a large proportion of yellow elastic fibres, 
w T hich give to the lung tissue a remarkable degree of 



THE ORGANS OF RESPIRATION. 131 

elasticity. The whole is completely enclosed by a serous 
membrane, thepletwa, which also lines the chest cavity. 

231. The Thorax. — The lungs are suspended in a 
closed box, the chest cavity, or thorax. The sides of the 
thorax are composed of the ribs, with the muscles and 
other tissues which cover the ribs and fill the spaces be- 
tween them. The backbone and the breastbone also 
help to form the chest walls. The under side of the 
cavity is closed by a broad muscle, the diaphragm, 
which separates it from the cavity of the abdomen. 

232. The Diaphragm. — This very important part 
of the respiratory apparatus is located, as just stated, 
between the chest and the abdomen. It is a muscular 
partition, the edges of which are attached to the lower 
ribs. When at rest, the diaphragm is dome-shaped, ris- 
ing up into the cavity of the chest. Its hollow under- 
surface rests upon the liver, stomach, and other organs 
which occupy the upper part of the- abdominal cavity. 
Besides the diaphragm, there are a number of other 
muscles attached to the outer surfaces of the ribs which 
assist in respiration. The abdominal muscles also are 
of essential use in breathing. 

SUMMARY. 

1. The chief parts of the respiratory apparatus are the air '-passages, 
the lungs, and the thorax. 

2. The air-passages include the mouili, nostrils, nasal cavity, pharynx, 
soft palate, ttvula, larynx, weal cords, epiglottis, trachea, and bronchial 
tubes. 

3. The lungs are chiefly made up of bronchial tubes and air-cells, 
and are covered by the pleura. 

4. The chief parts of the thorax are its framework of ribs, the mus- 
cles, diaphragm, and pleura. 



CHAPTER XVI. 
HOAV WE BREATHE. 

233. Two Acts in Breathing. — The air is first 
received into the lungs, then expelled. The first act 
is called, inspiration, the second expiration. By enlarge- 
ment of the chest cavity more room is made in the 
lungs, and air comes in to occupy the space. By an 
opposite change the space is diminished, and thus a 
portion of the air is driven out of the lungs. The size 
of the chest is increased by the contraction of muscles 
which draw the ribs upward and outward, and also by 
contraction of the diaphragm, which enlarges the chest 
downward. The diaphragm forms the floor of the chest, 
and, rising and falling, acts somewhat like the piston of 
a pump. The air is expelled from the lungs by the re- 
laxation of the muscles which enlarge the chest, by the 
natural elasticity of the lungs, and by the contraction of 
the abdominal muscles. 

The natural action of the lungs is much like that of a 
pair of bellows, except that the air passes alternately out 
and in at the same opening. Suppose the trachea to be 
the nozzle of the bellows, the lungs the body, and the 
points of the ribs on each side the two handles. When 
the muscles of inspiration contract, the points of the ribs 
are separated, just as the handles of a pair of bellows 
are drawn apart. This is well seen in the breathing of 



HOW \VK BREATHE. 133 

a long-distance runner and in the panting of a dog. The 
natural movement of the chest is greatest in the region 
of the waist. 

Respiration is carried on by voluntary muscles, which, 
by their connection with special nerve centres in the 
brain, are made to act involuntarily. 

234. Frequency of Respiration. — The rate of 
breathing is modified by various conditions and circum- 
stances, as age, position, and exercise. As a rule, the 
lungs act once for every four heart-beats. The average 
rate of respiration is sixteen to twenty each minute. We 
breathe more slowly during sleep. It is not ordinarily 
possible to hold the breath much more than half a min- 
ute, but by first taking several deep inspirations the 
breath may be held much longer. 

235. Modifications of Respiration. — Coughing is 
a series of spasmodic expirations. Hiccough is a single 
sudden inspiration, caused by spasmodic contractions of 
the diaphragm accompanied by closure of the larynx. 
It is usually caused by gas in the stomach. Sneezing is 
a single violent expiratory effort, in which the air is ex- 
pelled through both the nose and the mouth. Soiling 
is a series of short inspirations. Yawning is a long in- 
spiration with the mouth widely opened. Laughing con- 
sists of a series of short expiratory movements, accom- 
panied by agreeable emotions. 

236. Capacity of the Lungs. — The amount of air 
taken into the lungs in .an ordinary breath is about 
twenty -five cubic inches, or a little less than a pint. 
(Compute the amount breathed in twenty-four hours.) 
The amount of air which the lungs may contain is very 
much greater than that ordinarily used. After taking 
an ordinary breath, by a vigorous effort in expanding 



134 SECOND BOOK IN PHYSIOLOGY. 

the lungs, about one hundred cubic inches more may be 
inhaled. By a strong effort after breathing out an or- 
dinary breath about one hundred cubic inches more may 
be expelled. There is left in the lungs continually about 
one hundred cubic inches which cannot be expelled by 
a voluntary effort. Adding to these several amounts 
the twenty-five cubic inches ordinarily inhaled and ex- 
haled, we have three hundred and twenty -five cubic 
inches as the total contents of the lungs after taking 
in a very full breath. 

237. Composition of the Air. — The atmosphere 
consists of a mixture of two gases, nitrogen and oxygen, 
with a very small amount of carbonic acid gas, and va- 
rious other substances in greater or less abundance, 
according to the degree of impurity of the air. The 
proportion of the principal elements of the atmosphere 
is, in one hundred parts of the air, twenty-one parts of 
oxygen and seventy-nine of nitrogen. For convenience, 
we may say that the air consists of one part oxygen to 
four parts nitrogen. The proportion of carbonic acid 
gas does not exceed, in pure air, four to six parts in ten 
thousand. 

238. Properties of Oxygen. — Oxygen is the great 
supporter of life. Vegetables require oxygen, as do 
animals. They feed upon carbonic acid gas, separating 
the carbon from the oxygen, and thus purifying the air ; 
but their life processes depend upon oxygen as much as 
do those of animals. Oxygen is also the great supporter 
of combustion or burning. The fire in our stoves and 
grates requires oxygen to support it, just as animals re- 
quire this element to maintain life. The more oxygen 
a fire gets, the brighter it burns. This is why a good 
draft is essential for a good fire. In undergoing decay, 



HOW WE BREATHE. 135 

as well as in burning, substances combine with oxygen. 
Rotting is really a slow burning. When oxygen com- 
bines with any substance, as coal or wood, heat is pro- 
duced. The more rapid the combination, or burning, the 
more intense the heat. The slow burning of the rotting 
log produces just as much heat as would be produced by 
burning the log in a grate, but it is given off so slowly 
as to be imperceptible to the senses. 

239. Nitrogen. — The purpose of this gas seems to 
be to dilute the oxygen and regulate its supply to the 
body. It will not support combustion. 

240. Carbonic Acid Gas. — This gas possesses prop- 
erties very different from those of oxygen. It will not 
support combustion. A candle placed in it immediately 
goes out. Animals die when immersed in it. It is pro- 
duced in other ways than by burning, as by fermenta- 
tion, and by all forms of decomposition or decay. The 
air of fruit-houses, vegetable-cellars, and of brewers' vats 
often contains a large amount of this gas. It is also 
produced by chemical actions of various sorts. Great 
volumes of carbonic acid gas escape from volcanoes. 
It is also found in coal-mines., where it is known as 
"choke-damp." 

Carbonic acid gas is heavier than air, and hence some- 
times collects in low places in which the air is not dis- 
turbed, as in unused cellars, deep wells, mines, and some- 
times in deep valleys. A good test for this dangerous 
gas is a lighted candle or taper. Air which contains 
four parts of the gas in one hundred of air will put out 
a burning taper when placed in it, and will destroy ani- 
mal life almost as quickly. This test should be applied 
before entering a deep well, by letting down a lighted 
candle. Another test is lime-water, which becomes 



136 SECOND BOOK IN PHYSIOLOGY. 

milky in appearance when shaken up with air contain- 
ing carbonic acid gas in any considerable amount. 

241. The "Two Breaths." — The air which we 
breathe in and the air which we breathe out are very 
unlike. We take in at each ordinary breath about twen- 
ty-five cubic inches of air, of which about five cubic 
inches is oxygen, the rest nitrogen. When the air re- 
turns from the lungs it is found to have lost one and a 
quarter cubic inches of oxygen, and gained a cubic inch 
of carbonic acid gas, together with moisture, heat, and 
poisonous organic matter. 

The amount of water daily expelled from the lungs 
in the form of watery vapor is estimated at from half a 
pint to one and one-half pints. (See Experiment 13, 
page 274.) 

242. A Subtle Poison in the Breath. —The or- 
ganic matter which the expired breath contains, although 
very minute in quantity, is so poisonous in character 
that a very small amount will render a large volume of 
air unfit to breathe, and is even capable of producing 
death if inhaled. The eminent French physician, Dr. 
Brown-Sequard, recently made some interesting experi- 
ments with this poison. He found that a very minute 
quantity of it injected under the skin of small ani- 
mals caused almost instant death. An animal made to 
breathe air contaminated by the breath, and from which 
the carbonic acid gas has been removed, quickly dies. 
It is the retention of this poison in the body which so 
speedily causes the death of an animal deprived of air. 

243. Changes in the Blood during Respiration. 
— The changes which occur in the blood during respira- 
tion are the opposite of those which occur in the air. It 
loses carbonic acid gas, moisture, heat, and organic mat- 



HOW WE BREATHE. 137 

ter, and gains oxygen. The exchange of carbonic acid 
gas for oxygen changes the dark purple color of the 
venous blood to the bright scarlet of arterial blood. 

24 4. The Assimilation of Oxygen. — The respira- 
tory process is not confined to the lungs. It only be- 
gins and ends in the lungs. Every tissue needs oxygen. 
A muscle deprived of oxygen soon loses its power to con- 
tract. The whole vital machinery stops. Oxygen must 
be circulated to every cell and tissue in the body. The 
process of respiration really consists, then, in the inhala- 
tion, circulation, and assimilation of oxygen, and the cir- 
culation to the lungs and exhalation of carbonic acid gas 
and organic matter. 

245. Oxygen and Animal Heat. — One of the 
objects in breathing is to maintain animal heat. Heat 
results from the union of oxygen with the elements of 
the tissues. It is obvious that the more oxygen used 
in the body, the more heat will be produced. In winter 
we need more heat than in summer, and the air being 
denser, we take more oxygen into our lungs. 

The amount of heat daily produced within the body 
is the same as that which would result from the burn- 
ing of the food daily eaten. The body may be com- 
pared to a stove which is kept at a constant temperature 
by the burning of the fuel placed in it. The body of a 
grown person gives off in twenty-four hours heat enough 
to raise* one pound of water from zero to the tempera- 
ture of the body. The adipose or fatty tissue found in 
all parts of the body, and the glycogen, or animal starch, 
found chiefly in the liver and muscles, serve as fuel. 
The process of combustion, or heat production, is most 
active in the muscles, and is greatly increased by muscu- 
lar exercise. When little exercise is taken, while the 



138 SECOND BOOK IN PHYSIOLOGY. 

usual amount of food is still consumed, part of it is de- 
posited as a reserve tissue in the form of fat or gly- 
cogen, and the body gains in weight. When an un- 
usual amount of muscular exercise is taken without an 
increase in the amount of food, the fat or glycogen is 
consumed in greater quantities, and the body loses in 
weight. Vigorous exercise is thus a regulator of nutri- 
tion, and is the most important means of reducing weight. 

SUMMARY. 

1. Two acts in breathing, inspiration and expiration. 

2. Natural breathing is like the action of a pair of bellows ; as the 
chest. cavity is alternately enlarged and diminished, air is made to pass 
in and out. 

3. The chest cavity is made larger by the contraction of the muscles 
acting especially upon the sides of the chest, and the contraction of 
the diaphragm. The movement should be chiefly at the waist. 

4. The chest cavity is made smaller by relaxation of muscles, con- 
traction of lungs, and contraction of the abdominal muscles. 

5. Breathing is an involuntary act of voluntary muscles ; rate about 
sixteen to twenty per minute ; slower during sleep. 

6. Coughing, sneezing, laughing, are modifications of the act of res- 
piration ; hiccoughing, sobbing, yawning, are modifications of the act 
of inspiration. 

7. The total capacity of the lungs is three hundred and twenty -five 
cubic inches ; the amount ordinarily used in breathing, twenty-five 
cubic inches. 

8. Pure air contains one part of oxygen to four of nitrogen, and 
four to six parts of carbonic acid gas in ten thousand of air. 

9. Oxygen supports life, both animal and vegetable, and also com- 
bustion. 

10. Carbonic acid gas is a deadly poison to animals. It will not sup- 
port combustion. 

11. Air loses in the lungs one fourth of its oxygen, and gains car- 
bonic acid gas, organic matter, heat, and moisture. 

12. The organic matter is the most poisonous element of expired air. 

13. Respiration consists of the inhalation, circulation, and assimi- 
lation of oxygen, and the circulation and exhalation of carbonic acid 
gas and organic matter. 






CHAPTER XVII. 

HYGIENE OF THE LUNGS AND VENTILATION. 

216. The air we breathe is the most essential of all , 
the necessaries of life. Deprived of food, a man may 
live more than a month ; deprived of water, he may live 
a week ; but deprived of air, he will die in a few min- 
utes. Hence it is of the utmost importance that our 
gaseous food should be abundant in quantity and pure 
in quality. 

247. What is Impure Air? — Air which contains 
so large a proportion of foreign or poisonous elements 
as to be detrimental to health when habitually inhaled, 
is impure. 

248. Foul Gases. — Among the chief impurities 
found in the air are foul gases. The most important of 
these are carbonic acid gas, of which we have already 
learned ; carbonous oxide, a still more deadly gas, which 
escapes from stoves with defective flues or closed damp- 
ers in the stove-pipe ; and various noxious gases which 
emanate from sewers, and are known as sewer gas. 

A few years ago (1885) the newspapers announced the 
death of five men who were engaged in cleaning a sew- 
er. In this instance death occurred very suddenly, with- 
in a few moments of the first unpleasant symptoms. 
Thousands die every year of slow poisoning from this 
source. 

Poisonous gases of a deadly character are driven 



140 SECOND BOOK IN PHYSIOLOGY. 

off from cesspools, vaults, decaying vegetable or animal 
matter, such as is found in barn -yards, animal -pens, 
garbage-heaps, vegetable-cellars, etc. 

The great amount of poisonous gases given off by 
decomposing animal matter is shown by the fact that 
buzzards and other scavenger-birds may often be seen 
circling above the carcass of an animal, at so great a 
distance as to be scarcely visible. 

Wall-papers sometimes contaminate the air with pois- 
onous gases from arsenical colors. Mouldy walls, musty 
closets, damp and musty beds and bedchambers, are 
other sources of foul gases. 

249. Disease Germs. — These microscopic forms of 
life are always present in great numbers in the air 
about places where animal or vegetable substances are 
undergoing decay. Foul cellars, neglected cisterns, stag- 
nant pools, are all sources of foul air and germs. We 
have already learned that germs are the most dangerous 
of all enemies to life and health. 



* 



• ••« •*• 

••••••• •• 

•/ • * • 

.•-;.•••■• 
• : v.- . • • 

• • • * % « * 

• # s • • 

Fig. 24. — Germs. {Greatly magnified.) 

250. Sewer Gas. — Sewers are pipes or passages 
underground through which filth of various sorts is 
drained off, usually into some river or large body of 




HYGIENE OF THE LUNGS AND VENTILATION. 141 

water. Sewers always contain foul air, laden with 
germs, which is called sewer gas. Whenever a house is 
connected with a sewer there is danger of poisoning 
from sewer gas. To prevent injury from this source 
the sower should be ventilated, before it enters a build- 
ing, by a pipe running up to the open air ; and every 
sewer -pipe which enters a building should be carried 
straight up through the building and the roof, so that 
there may be no accumulation of sewer gas in the pipe. 

251. Coal Gas. — In cities where coal gas is used 
for lighting purposes, cases of poisoning frequently occur 
from carelessness in its use, or from leaky pipes. Coal 
gas owes its deadly properties to the carbonous oxide 
which it contains. The recently introduced " water 
gas" is particularly dangerous, as it consists very large- 
ly of carbonous oxide. The greatest care should be taken 
to prevent contamination of the air with these gases. 
The slightest odor of gas should be at once traced to 
its source and the leak stopped. A suffocative gas is 
given off by kerosene lamps when the flame is turned 
low. Kerosene stoves give off harmful gases under the 
same circumstances. Gasolene stoves are particularly 
dangerous on account of the fact that gasolene vapor- 
izes very rapidly when unconfined, and a mixture of gas- 
olene with air is highly explosive. Many fatal accidents 
have occurred from the careless use of gasolene. 

Night air is by many regarded as exceedingly un- 
wholesome, and they accordingly carefully close win- 
dows and doors at night, to exclude it as thoroughly as 
possible. These persons seem to forget that night air is 
the only air we have at night, and that we must breathe 
it if we breathe at all. The air of night is necessarily 
night air, whether in-doors or out-of-doors. In any case, 



142 SECOND BOOK IN PHYSIOLOGY. 

pure night air must be more wholesome than air which 
has been rendered foul by breathing. 

252. Dust. — Another common impurity of the air 
is dust from various sources. The little motes which 
"dance in the sunbeam" are, on examination, found to 
be "germs" and small particles of many different sub- 
stances. Dust occurs in connection with some manu- 
facturing industries in such quantities that it becomes 
a dangerous source of disease, sometimes collecting in 
the lungs and causing asthma or consumption. Street 
dust is largely composed of germs. The inhalation of 
dust of any sort should be carefully avoided. 

253. Air-filters. — Professor Tyndall, the eminent 
English scientist, made the useful discovery that cotton- 
wool is a perfect filter for both dust and germs. Air- 
filters should always be worn by persons employed in 
dusty occupations. A cotton handkerchief doubled, and 
tied closely over the mouth and nose, serves as a very 
useful filter when one is unavoidably exposed to dust. 

254. Disinfection. — Sources of germs and foul gases 
should not be allowed to exist in connection with hu- 
man dwellings. Foul matters should be removed from 
the premises at once. Garbage may be burned, or, if 
not, should be removed daily. 

Sunlight, fresh air, and scrupulous cleanliness are 
among the most efficient of all disinfectants. In dwell- 
ings where light and air have free access, mould, mil- 
dew, and germs do not flourish. We should admit these 
powerful disinfectants into our houses as freely as possi- 
ble. A house or room that has a stale or musty odor 
is unfit to live in. It should be well disinfected. Pan- 
tries, basements, closets, and store-rooms need to be thor- 
oughly cleaned and disinfected frequently. There is no 



HYGIENE OF THE LUNGS AND VENTILATION. 143 

better practical means for accomplishing this than the 
burning of sulphur in the place to be disinfected, after 
it has been thoroughly cleared or cleaned. Chloride of 
lime is also an excellent disinfectant. In using sulphur 
for disinfection, burn at least three pounds for each one 
thousand cubic feet of space to be disinfected. A solu- 
tion of chloride of lime, one pound to the gallon of wa- 
ter, is useful for the disinfection of drains, and soiled 
vessels, garments, or surfaces. Further directions re- 
specting the use of disinfectants can be obtained from 
a physician or a druggist. 

255. Breath-poisoned Air. — As we have learned, 
air which has been breathed contains a deadly poison. 
Small animals placed in such air speedily die. Very 
small quantities of the poison contained in breathed air 
may produce disease and ultimate death, even though 
the immediate effects may not be serious. Consumption 
is doubtless often caused by breathing air which has 
been rendered impure by respiration. The headache, 
colds, loss of appetite, nervousness, and mental dulness 
with which school children often suffer may be justly 
charged, in many instances, to breathing impure air in 
the school-room. 

Many years ago one hundred and forty-six English 
soldiers were taken prisoners of war in India, and shut 
up in a small room eighteen feet square, having only 
two small openings on one side. In a short time the 
air became so poisonous that the most intense suffering 
began, which resulted in the death of all but a few who 
were able to keep themselves near the windows. Be- 
fore midnight many were dead, and at six o'clock in the 
morning only twenty-six persons still breathed, lying in 
an unconscious condition. These, being removed to the 



144 SECOND BOOK IN PHYSIOLOGY. 

open air, were revived, but many of them never fully 
recovered from the effects of the sufferings of that ter- 
rible night. 

256. Ventilation. — The purpose of ventilation is to 
exchange the air which has been rendered impure by 
breathing, or otherwise, for pure air, or to dilute the im- 
pure air to such an extent as to render it harmless. 
Every building occupied either by human beings or by 
animals should have proper arrangements for the regu- 
lar and abundant supply of pure air. This is ventila- 
tion. There are several facts respecting ventilation 
which it is very important for us to understand as 
clearly as possible, and which we may now consider. 

257. How Much Air is Required ? — Careful in- 
vestigations by Dr. Parkes, of England, and other sci- 
entists, show that each breath of expired air renders unfit 
to be breathed at least two cubic feet or half a barrelful 
of air. As we breathe eighteen times a minute, a little 
figuring will show that we spoil at least two thousand 
cubic feet of air each hour of our lives. It is evident, 
then, that we require each hour two thousand feet of 
pure air to take the place of the air which we render 
impure by breathing. 

258. How to Ventilate. — In the summer-time, 
when doors and windows may be widely opened, an 
abundant supply of fresh air is readily obtained ; but 
in cold weather, when doors and windows cannot be 
opened without harmful draughts, some regular means 
of supplying pure air must be relied upon. Each room 
must have at least two openings — one to admit fresh 
air, the other to allow impure air to pass out. We may 
call these openings respectively the fresh-air inlet and 
the foul-air outlet. 



HYGIENE OF THE LUNGS AND VENTILATION. L45 

259. The Fresh - air Inlet. — The air should be 
warmed, before it enters the room, by a furnace or other 
means, or the fresh air may be warmed by a stove or a 
steam-coil placed over the fresh-air inlet. The size of 
the opening should be such as to provide at least eighteen 
square inches for each person, or thirty square inches 
if the opening is covered by a register. Ten persons 
require an opening ten times as large as one person, and 
for a thousand persons a proportionate amount of space 
for the admission of fresh air must be provided. The 
fresh-air inlet may be placed at the floor or at the ceil- 
ing, as is most convenient. 

260. The Foul-air Outlet. — The opening for the 
outlet of foul air should be placed at the floor if the fresh 
air is admitted warm. Warm fresh air, on entering a 
room, rises at once to the ceiling. As it cools, it grad- 
ually falls to the level of the floor, at the same time be- 
coming more and more impure. Windows and outside 
walls are cooler than inside walls, and hence the air 
falls chiefly at the windows and the outer walls of a 
room. For this reason, also, it is best to place the foul- 
air outlet beneath or near a window. The size of the 
foul-air outlets should be at least as great as that of the 
fresh-air inlets. It is better that the area of outlets 
should be somewhat greater than that of inlets. (See 
Experiment 14, page 274.) 

When fresh air is admitted cold, the foul-air outlets 
should be placed a few feet above the floor, as the pure 
air, being cold, will be found near the floor, and the 
most impure in the upper part of a room. 

Foul-air openings must be connected with a ventilat- 
ing shaft in which there is a constant upward draught. 
A strong draught can best be obtained by heating the 
7 



146 SECOND BOOK IN PHYSIOLOGY. 

shaft. If the shaft is built in an inside wall, heat in the 
shaft is not necessary, unless a very strong draught is re- 
quired, but shafts in outside walls must always be heated 
to secure a constant and efficient draught, especially in 
cold weather. The area of a cross section of a ventilat- 
ing shaft should be equal to the combined areas of the 
foul-air outlets. 

261. Moisture of the Air. — A useful constituent 
of the atmosphere which has not yet been considered is 
watery vapor, or moisture. The air is capable of dis- 
solving and rendering invisible a considerable amount 
of water, of which it always contains more or less. If 
the air is too dry the exchange of gases in the lungs 
does not take place readily, and when the air is saturated 
with moisture it does not readily take up the moisture 
which should escape from the lungs, and with which the 
organic poison of the breath is removed. The action of 
the skin is also lessened in an excessively moist atmos- 
phere. The interference with the action of these two 
important organs is the cause of the discomfort expe- 
rienced in a warm, moist atmosphere, as just before a 
rain on a hot day. 

In winter-time, when the air which enters our houses 
may be so dry as to be injurious to health and pro- 
ductive of discomfort, we may add moisture to the air 
by boiling water. It is for this purpose that hot-air 
furnaces are supplied with water-pans. 

262. Lung Hygiene. — Having secured an ample 
supply of pure air by suitable ventilation, it is important 
that it should be properly used. We may breathe more 
rapidly or less rapidly, deeper or more superficially, as 
we choose. We may expand our lungs so that they 
will exchange nearly a gallon at each breath, or we 



HYGIENE OF THE LUNGS AND VKXTIL.YTIOX. 1 17 

may make so little effort in breathing that only a few 
cubic inches of air pass in and out the lungs as we 
breathe. Thus it becomes a matter of importance that 
we should attend carefully to the manner in which we 
breathe. The whole chest should be expanded. Civil- 
ized women generally use only the upper part of the 



Costal. 



Waist 



Costal. 



Waist. 



r 



WOMAN IN CORSET. 



Costal. 



Waist. 



MAN IN CoEBliT. 



Costal. 



Waist. 



WOMAN WHO NEVER WOKE A CORSET. 



Costal. 



Waist. 



CHIPPEWA INDIAN WOMAN. 



Fig. 25. — Breathing Movements as Registered by the Pneumograph. 



lungs, their unhealthful mode of dress making it im- 
possible for them to use the lower part of the chest 
properly, while men expand the lower part of the chest 
most. Among savages, men and women breathe alike. 
By the aid of the pneumograph the author has made 
many careful observations among Indian and Chinese 
women, who wear their clothing loose about the waist, 



148 SECOND BOOK IN PHYSIOLOGY. 

the Yuma Indians of New Mexico, and other Indian 
tribes, who have not yet adopted the civilized mode of 
dress, the peasant women of Italy, and in Paris among 
women known as models, who are not allowed to wear 
corsets or tight bands, and has been unable to discover 
anything suggesting the slightest difference between 
the natural mode of breathing in men and in women. 
The accompanying cuts are exact copies of tracings of 
the respiratory movements obtained by the author by 
the aid of the pneumograph. The first half of each 
tracing shows the movements made by the upper part 
of the chest in ordinary breathing, the second half the 
movements of the lower part of the chest. It will be 
at once seen that the tracing produced by the breathing 
of the Chinese woman is the same in character with 
that obtained from a man, while that obtained from the 
corset- wearing woman is just the reverse. 

For healthful breathing it is necessary that the cloth- 
ing should be loose at the waist. To wear the clothing 
tight at the waist is as absurd as to tie the handles of a 
pair of bellows needed for constant use, and cripples the 
lungs in precisely the same manner. The lower part of 
the chest is so constructed as to allow of easy expansion, 
while the upper part is completely enclosed by bones and 
cartilages. Women and girls, as well as men and boys, 
should accustom themselves to the use of the whole 
chest by daily vigorous exercise in loose garments. It 
is especially important to cultivate the use of the lower 
portion of the chest and of the abdominal muscles. 

Students and persons whose occupations do not give 
them an abundance of arm exercise should devote at 
least one-half hour daily to such special exercises as will 
strengthen the muscles of the arms and chest. The use 



HYGIENE OF THE LUNGS AXI) VENTILATION. 149 

of wooden dumb-bells and Indian clubs is excellent for 
this purpose. What are known as "free-hand move- 
ments " of the arms are also useful. Simply raising the 
extended arms from the side upward as far as possible, 
keeping the shoulders well thrown back, and rising upon 
tiptoe at the same time, is a good exercise for the lungs. 
The movements should be repeated at the rate of about 
ten or twelve a minute, and continued for ten minutes 
two or three times a day. 

The action of the diaphragm is important in reference 
to other organs besides the lungs. It aids digestion by 
a sort of kneading action upon the stomach. It com- 
presses the liver, empties it of its stagnant blood, and 
forces the bile into its proper channels. It hastens the 
sluggish current of the portal circulation, and thus aids in 
the absorption of digested food by the mucous membrane 
of the stomach and the intestines. Its great importance 
demands that it should be allowed to act without the 
restraint of tight stays or waistbands. The practice of 
tight lacing, so common among civilized women (though 
not practised by the women of any ^^civilized tribe yet 
discovered), is so exceedingly harmful, and productive of 
such wide-spread injury in the body, that it can scarcely 
be considered less than criminal when practised by a 
person Avho has been informed of its evils. 

263. Colds A cold is often a more serious matter 

than many persons suppose. A " cold in the head" is the 
common cause of nasal catarrh, a very annoying and 
often offensive disease. A "cold on the lungs" may 
lay the foundation for fatal disease of these organs. 
The greatest care should be taken to avoid colds. An 
excellent means to prevent taking cold is a cool sponge 
bath taken every morning. Never neglect a cold. 



150 SECOND BOOK IN PHYSIOLOGY. 

264. Mouth-breathing. — Many persons acquire the 
very harmful habit of breathing through the mouth. 
Air should always enter the lungs through the nose. 
The nose not only acts as a strainer but warms the air, 
moistens it to some extent when it is too dry, and warns 
us of danger when it is impure. Mouth-breathing is the 
cause of snoring. It is usually occasioned by some dis- 
ease of the nose which obstructs the nasal passages. 
As a result of habitual mouth-breathing, the lungs be- 
come diseased, and frequently a peculiar deformity of 
the chest, familiarly known as " pigeon breast," is pro- 
duced. Sometimes, also, as a result of mouth-breathing, 
the features become unpleasantly distorted, the upper 
lip being shortened and the upper teeth projecting. A 
physician should always be consulted when mouth- 
breathing is found to be constant. 

265. Suffocation and Drowning require the use of 
artificial respiration, which should be applied intelli- 
gently and patiently for half an hour or longer, if nec- 
essary. (See Experiment 15, page 275.) In the mean 
time keep the patient warm by the use of hot bottles. 

When a person must be exposed to noxious gases or 
smoke, as in escaping from a burning building, suffo- 
cation may be prevented by taking several very deep 
breaths before the exposure, as this will enable one to 
hold the breath for a much longer time than usual. If 
obliged to go through hot smoke and gases, tie a wet 
handkerchief over the mouth and nose before making 
the attempt, and keep the head as near the floor as pos- 
sible. 

266. Choking. — As we have elsewhere learned, sub- 
stances swallowed are prevented from entering the air- 
passages by means of the epiglottis. If one is trying 



HYGIENE OF THE LUNGS AND VENTILATION. 151 

to speak and eat or drink at the same time, the epiglot- 
tis sometimes tails to close properly, so that substances 
may enter the larynx and cause choking. Death has 
resulted from the injury to the lung caused by so small 
an object as a kernel of corn. Larger objects may 
produce death by obstructing the breath. A choking 
person should be held head downward. If relief is not 
speedily obtained by this means, a few smart blows be- 
tween the shoulders will often dislodge the foreign body. 
If these measures do not succeed promptly, send for a 
surgeon at once. 

267. Injurious Effects of Alcohol — The effect of 
alcohol in predisposing to inflammation of the bronchial 
tubes, pneumonia, and various other grave diseases of 
the lungs, is well known to physicians. Alcohol dilates 
the small blood-vessels of the lungs as well as those of 
other parts of the body, and thus invites congestion and 
inflammation. Alcohol was once regarded as an excel- 
lent remedy for consumption, and was very generally 
recommended as such by physicians ; but recent studies 
of this subject have shown that alcohol is itself a cause 
of one of the most hopeless forms of consumption. 

268. Tobacco — Smoking is a very common cause of 
serious disease of the throat. Sometimes cancer of the 
throat results from excessive smoking. Cigarette-smok- 
ing is also a cause of disease of the nose as well as of 
the lungs. The use of tobacco in any form is detrimen- 
tal to the health of the lungs, since it injures the whole 
body, lowers vitality, and hence lessens the resistance to 
disease. 

The breath of the tobacco-user is evidence of the 
polluted state of his body. His brain, nerves, muscles — 
all the tissues — are flavored with nicotine. His blood is 



152 SECOND BOOK IN PHYSIOLOGY. 

loaded with the poison, which it carries to the lungs, 
liver, kidneys, and skin for elimination. This accounts 
for the odor which hangs upon the breath of the smoker 
often for hours or days after his last cigar or pipe. His 
whole body is saturated with the poison. 

SUMMARY. 

1. Chief air impurities — carbonic acid gas, carbonous oxide, sewer 
gas, gases of decay, coal gas, kerosene and gasolene gas, germs, dust, 'poi- 
son of the breath. 

2. Germs are the most dangerous of all. 

3. Disinfectants — pure air, sunlight, fire, sulphur fumes, chloride of 
lime. 

4. Amount of air needed — 2000 cubic feet per hour for each person. 

5. Two openings required — inlet, outlet. 

6. Admit warm air near floor, allowing thirty inches of register sur- 
face for each person. 

7. The foul-air outlet should at least equal the inlet in size, and 
should be placed at the floor and connected with a ventilating shaft. 

8. Lung exercise is needed. Expand chest at waist ; use diaphragm 
and waist muscles. 

9. Proper breathing specially aids the stomach and the liver as well 
as the whole body. 

10. Mouth-breathing is very injurious to health. 

11. For suffocation or drowning, employ warmth and artificial respi- 
ration. 

12. Alcohol causes inflammation of lungs and consumption. 

13. Tobacco-using causes disease of throat and nose» 



CHAPTER XVIII. 

THE VOICE AND SPEECH. 

260. The Larynx. — As we have already learned, the 
larynx is the organ of the voice. It is a cartilaginous 
box, placed between the windpipe and the pharynx. 
The location of the larynx is indicated by the promi- 
nence familiarly known as " Adam's apple." 

Within the larynx are found two bands of tissue 
which stretch across it, called the vocal cords. By 




Fig. 26. — Vocal Cords. 



means of various muscles, the vocal cords may be 
stretched tightly or relaxed, drawn together, or sep- 
arated from each other. The upper opening into the 
larynx is guarded by the epiglottis, which has been else- 
where described. 



7* 



154 SECOND BOOK IN PHYSIOLOGY. 

270. Voice. — When the vocal cords are brought to- 
gether, and air is forced through between them, they are 
made to vibrate, producing a sound. This is the voice. 
When the vocal cords are long or loosely stretched, the 
voice is low in pitch. When the cords are short, or 
tightly stretched, the pitch is high. A grown person 
has a larger larynx than a child, and hence longer vocal 
cords and a voice of lower pitch. As a child develops, 
the larynx enlarges, especially between the ages of four- 
teen and eighteen. This is the reason why the voice 
changes at this period of life. A man has a larger lar- 
ynx, and hence a voice of lower pitch, than a woman. 

271. Speech is produced by modifications of the voice 
made by the tongue, teeth, lips, and throat. Whis- 
pered speech is produced by making the usual move- 
ments of the mouth without using the vocal cords. 

The singing voice differs from the ordinary voice only 
in the fact that a succession of sounds having a har- 
monious relation is uttered, instead of mere vocal sounds 
or words without relation to harmony or musical laws. 
The volume of the voice depends chiefly upon the size 
of the vocal organs, the quality upon their form and 
that of the nasal cavity. The range of the ordinary 
voice is scarcely two octaves, but the voices of some 
celebrated singers have had a range of three or four 
octaves. The limits of the human voice are represented 
by 42 vibrations per second for the lowest tone, and 
over 2000 vibrations per second for the highest. 

272. The Hygiene of the Voice. — Avoid taking 
cold. If a cold has been taken, and is accompanied by 
hoarseness, the voice should not be used in singing or 
loud speaking until the hoarseness is relieved. Perma- 
nent injury to the voice often results from disregarding 



THE VOICE AND SPEECH 155 

this rule. Never overstrain the voice. Cultivate full 
tones, using* the muscles of the waist in singing and 
speaking instead of the upper part of the chest. The 
practice of intoning is injurious to the voice, inducing 
chronic inflammation, which destroys the finer qualities 
of the voice. The use of rich foods and irritating con- 
diments or sauces impairs the voice, by producing con- 
gestion of the throat. 

273. Alcohol and Tobacco. — The use of alcohol or 
tobacco frequently causes loss of voice or great and 
irreparable injury to it. The deep-toned voice of the 
beer-drinker is an indication of chronic inflammation of 
the larynx, a disease to which drinkers of beer are sub- 
ject. Tobacco - users, particularly smokers, are seldom 
free from disease of the throat. The hot, irritating 
smoke, brought into contact with the delicate vocal 
cords, is productive of almost certain mischief. Singers 
and public speakers are often obliged to abandon the 
use of tobacco on this account. 

SUMMARY. 

1. Voice is produced by the vibration of the vocal cords ; speech, 
by modifications of the voice by the tongue, teeth, lips, and palate. 

2. Frequent colds, the use of condiments, and the practice of inton- 
ing injure the voice. In singing and loud speaking, use the diaphragm 
and the abdominal muscles, and expand the lower part of the chest. 

3. Alcohol and tobacco cause disease of the throat and loss of voice. 



CHAPTER XIX. 
THE SKIN AND THE KIDNEYS. 

274. The Skin.— The skin covers the entire body. 
At the openings of the body it joins the " lining skin," 
or mucous membrane. The skin is a very elastic tissue, 
and may be stretched to a surprising extent, as is seen 
in cases of great obesity or dropsy. This is due to the 
fact that the basis of its structure is a mesh-work of 
connective tissue, in which yellow elastic tissue abounds. 

The total area of the skin in an adult of average size 
is estimated to be about seventeen and one-half square 
feet. 

275. The Cuticle. — The skin is divided into two 
distinct layers. The outer, known as the scarf skin, cu- 
ticle, or epidermis, is composed of flattened cells, ar- 
ranged in several layers. The deepest laj^ers of the epi- 
dermis contain cells in which are colored granules, to 
which is due the color of the skin. In the white races 
the color granules are very few in number, while in the 
dark races they are very abundant. In the albino, the 
color cells are absent, so that the cuticle is nearly trans- 
parent, and shows the pink color of the tissues beneath. 

The scarf skin contains no blood-vessels and few 
nerves, and hence is not sensitive, and does not bleed 
when cut. By scraping the skin with a sharp knife the 
scarfskin may be removed without pain. In a blister, 
the cuticle is separated from the true skin. The epi- 



THE BKIN AND THE KIDNEYS. [57 

dermis is constantly shed, being rubbed off by the 

friction of the clothing and contact with other objects. 
After taking a warm bath, the outer and older layers of 




Fig. 21.— The Structure of the Skin. 

cells may be rubbed off in considerable quantity by the 
aid of a flesh-brush or a coarse towel. Soap and alkalies 
soften the dead cuticle and aid in its removal. The 
chief use of the cuticle is to cover and protect the sen- 
sitive structures beneath it. 



158 SECOND BOOK IN PHYSIOLOGY. 

276. The True Skin. — The deep layer of the skin, 
called the dermis, or true skin, contains many blood- 
vessels, glands, and nerves. The true skin also contains 
many involuntary muscular fibres, most of which are 
connected with hairs. The contraction of these fibres 
gives rise to the condition commonly termed " goose 
flesh." 

277. The Perspiratory Glands.— By looking close- 
ly at the palm of the hand with a magnifying-glass (such 
a glass as is used by students in the study of flowers 
will answer very well), numerous depressions may be 
seen all along the summits of the fine ridges which ap- 
pear on this portion of the skin. These depressions 
mark the openings of the so-called pores of the skin. 
Each is the mouth of a minute duct or tube, which runs 
down into the deep parts of the dermis, where it is 
curved upon itself in such a manner as to form a deli- 
cate coil, known as a perspiratory or sweat gland. 

The number of sweat glands and ducts in the entire 
skin is not less than two and one-half millions, making 
a total length of several miles. 

278. The Perspiration. — The perspiratory glands 
constantly pour out upon the skin a fluid excretion, the 
perspiration, or sweat, which consists of water and vari- 
ous impurities separated from the blood by the glands. 
In some parts of the body, as in the armpits, these 
glands are more numerous than in other parts. Ordi- 
narily, the perspiration escapes by evaporation as rap- 
idly as produced, so that it is unnoticed, and on this ac- 
count is termed insensible perspiration. The amount of 
insensible perspiration produced daily by the entire skin 
is usually from one and one-half to four pints. Extreme 
heat, active exercise, and other causes may give rise to 



TUK SKIN AND THE KIDNEYS. 



159 



much more profuse secretion, which becomes visible as 
sweat or sensible perspiration. When one is in a very 
damp atmosphere, the perspiration is not evaporate* 1 
with ordinary rapidity, and hence becomes visible. In 
fever the sweat glands are often paralyzed, so that the 
skin is dry, notwithstanding the excessive heat. The 
importance of the perspiration as an excretory fluid is 
well shown by the ill consequences which result when 
the action of the skin is checked, as in taking cold. 

279. The Sebaceous Secretion. — In addition to the 
sweat glands, there are to be found in the skin little 
glands known as sebaceous or oil glands, which form 
and pour upon the skin an oily substance, the purpose 
of which is to protect and lubricate 
the skin and to soften the hair. 

280. The Hair. — Hairs are 
found upon all parts of the surface 
of the body, with the exception of 
the palms of the hands and the 
soles of the feet. Each hair grows 
from a pouch in the skin, which ex- 
tends into its deepest parts. Many 
of the sebaceous Hands discharge 
their secretion into the hair tubes. 
The color of the hair is due to the 
presence of colored granules like 
those which give the skin its color. 

281. Uses of the Hair.— The 
uses of the hair seem to be chiefly 
(1) to protect the skin or parts be- 
neath from changes of tempera- 
ture, as in the case of the head ; (2) to protect sensitive 
parts from dust or other foreign substances, as do the 




Fig. 28. — The Root of a 
Hair. 



160 SECOND BOOK IN PHYSIOLOGY. 

eyelashes and eyebrows, and the hairs of the nostrils and 
of the external canal of the ear; (3) to serve as an aid 
to the sense of touch. 

282. The Nails. — These structures, like the hair, are 
appendages of the cuticle, or scarf skin. They grow from 
a little fold of the skin, and from the tissues which they 
overlay. Their use is to protect the ends of the fingers 
and toes, to increase the delicacy of the sense of touch, 
and to aid the fingers in picking up small objects. 

283. Uses of the Skin. — The skin is one of the most 
important organs of the body. Its chief uses are, (1) pro- 
tection ; (2) sensation — pain, touch, temperature ; (3) ex- 
cretion; (4) absorption; (5) respiration — absorption of 
oxygen and exhalation of carbonic acid gas ; (6) reg- 
ulation of temperature. 

The last-named use is probably one of the most im- 
portant functions of the skin. The internal temperature 
of the body, as we have elsewhere learned, is maintained 
at 98^° Fahr. At all seasons and in all countries the 
variation within the limits of health is scarcely more 
than one degree, notwithstanding the fact that the tem- 
perature of the air may vary from 70° Fahr. below zero, 
in the arctic regions, to 150° Fahr. above zero in the sul- 
try deserts of Northern Africa. 

It is evident that the body must possess some means 
by which its temperature may be nicely regulated or 
adjusted to the temperature of the surrounding atmos- 
phere. When we become much heated, we perspire 
freely. If we sit down in the shade after violent exer- 
cise on a warm day, as the perspiration dries off we feel 
cool, or even chilly. From this common experience we 
learn that the object of profuse sweating is to cool the 
body. This is accomplished by evaporation, which is a 



THE SKIN AND THE KIDNEYS. 



lfil 



powerful means of lowering the temperature. The 
body is being cooled in this way continually by the 
evaporation of the insensible perspiration. 

281. Relation of the Skin to other Organs. — When 
the action of the skin is suddenly checked, extra labor 
is thrown upon the lungs, liver, and kidneys, especially 
the latter. This may result in serious disease. Inflam- 
mation of the kidneys is often caused in this way. 

An animal, if covered with varnish, dies in eight or 
ten hours. At the coronation of Pope Leo X. a small 
boy was covered with gold-leaf to represent a cherub. 
In a short time he became very sick and in a few hours 
died, in spite of all that the most skilful physicians 
could do for him, poisoned by retained perspiration. 

285. The Kidneys.— These important organs are lo- 
cated at the back part of the abdominal cavity, just be- 
low the last ribs. They are placed 

clo^e to the spinal column, one on 
each side. Their shape is that of 
a kidney-bean. Their weight is 
from four to six ounces each. 

286. Structure of the Kid- 
neys. — The minute structure of 
the kidneys is remarkably simi- 
lar to that of the true skin, which 
it also resembles in its functions. 
When examined under the micro- 
scope, the substance of the kidney 
is found to be largely made up of 
very delicate tubes, which begin 
near the surface of the organ in 
delicate little round sacs, each of which contains a minute 
blood-vessel coiled up, as is shown in Figure 29. These 




Section of Kidney. 



162 SECOND BOOK IN PHYSIOLOGY. 

tubes combine as they pass towards the centre, becom- 
ing larger in size, and finally opening into a cavity in 
the kidney. This cavity communicates with a long tube, 
the ureter, which passes downward and empties into a 
large muscular sac, the bladder, located in the pelvis. 

287. The Urinary Excretion. — This is one of the 
most important of all the excretions, containing some of 
the most poisonous of the waste elements of the body. 
When from any cause the action of the kidneys ceases, 
the individual dies in a few hours, with all the symptoms 
of poisoning. 

SUMMARY. 

1. The skin is an elastic membrane, composed of two distinct lay- 
ers, — the outer called the cuticle, or epidermis, and the inner the dermis, 
or true skin. 

2 The cuticle is made up of several layers of cells, the lowest of 
which contains the coloring matter of the skin. 

3. The true skin contains nerves, blood-vessels, the sweat glands, and 
the sebaceous or oil glands. 

4. The amount of perspiration produced daily is one-half pint to 
two pints. 

5. The hair and the nails are appendages of the cuticle. They serve 
to protect the parts from which they grow. 

6. The uses of the skin are protection, excretion, absorption, regulation 
of the temperature of the body, and respiration. The skin is also an 
organ of sensation. 

7. The kidneys resemble the skin in structure and function. 

8. Their secretion is conveyed by the ureters to the bladder. 

9. The urinary excretion is one of the most important of all the ex- 
cretions of the body. 



CHAPTER XX. 

HYGIENE OF THE SKIN AND THE KIDNEYS. 

The two great requirements of health, as regards the 
skin, are proper clothing and cleanliness. These two 
conditions are as necessary for the health of the body- 
in general as for that of the skin, and hence should re- 
ceive ample and careful attention. 

288. Cosmetics. — The various lotions, powders,paints, 
creams, etc., which are sold for the purpose of beautify- 
ing the complexion, are to be looked upon with suspi- 
cion. Many of them are worthless ; others are danger- 
ous, not only injuring the skin, but producing grave 
disease. A form of paralysis which frequently occurs 
from this cause is known as " wrist-drop," from the fact 
that the hands hang down when the arms are stretched 
out, the patient not being able to raise them. Thorough 
cleanliness of the skin of the face, using soft water, either 
cold or tepid, aided by a little fine soap, is generally all 
the cosmetic required. A healthy skin is usually clear 
and beautiful, although there are, of course, differences 
in complexion, due to the amount and distribution of 
the coloring matter. Muddiness of the complexion is 
usually the result of bad diet and imperfect excretion. 
It may generally be made to disappear by the aid of 
proper bathing and care in diet, abstaining from rich 
foods, especially pastry, pork, and sausage. 

289. Care of the Hair. — The free use of hair-oils is 



164 SECOND BOOK IN PHYSIOLOGY. 

not necessary, and is decidedly unwholesome. Nature 
has provided the hair with oil glands, which pour out 
their secretion at the root of each hair, thus furnishing 
a natural dressing. If the scalp is kept in a healthy 
condition by frequent cleansing and daily brushing, a 
sufficient amount of oil will be produced to give the hair 
the desired lustre and softness. Hair-oils become rancid 
in the hair and gather dust : they should be avoided. 

Gray hair is the result of the failure of the cells which 
form the hair to produce the proper amount of pigment. 
It may be the natural result of age, or may be produced 
early in life by disease. 

Many of the "hair-dyes" and "hair restoratives" which 
are sold are poisonous, and are harmful both to the hair 
and to the general health. The use of hair-dyes by old 
persons to conceal their age is not in good taste, and 
rarely accomplishes the purpose desired. 

290. Care of the Nails. — The ends of the nails should 
never be bitten or torn off, but should be carefully 
trimmed with a sharp knife or scissors. The skin at 
the root of the nail should be carefully pushed back 
once or twice a week, to prevent its clinging to the nail 
and becoming torn. When the growth of the nail length- 
wise is interfered with, as when a person wears a shoe or 
boot which is too short or narrow at the toe, the side of 
the nail often grows down into the flesh, producing an 
ingrowing nail. 

291. Corns and Callus are due to excessive develop- 
ment of the cuticle, or scarfskin. They are usually the 
result of wearing tight or badly fitting shoes or boots. 
They may be easily removed, but will return so long as 
the cause remains. 

292. Burns and Scalds are the result of exposure to 



HYGIENE OF THE SKIN AND THE KIDNEYS. 1G5 

excessive heat, dry or moist. If the skin is injured 
through its entire thickness, a serious scar will be left 
behind. The pain of a burn is best relieved by apply- 
ing moistened soda and protecting the part from the 
air. Submersion in water is one of the best means of 
treating a serious burn. 

293. Effects of Alcohol and Tobacco upon the 
Skin. — Not even the skin escapes the ravages of these 
powerful poisons. The drunkard's nose and face show 
clearly the injury which alcohol is working in his body. 
The tawny skin of the tobacco devotee distils through 
its pores the foul poison which, having permeated every 
other organ, leaves behind its stain upon the delicate 
tissues of the beautiful covering of the body. 

294. Effects of Other Narcotics. —It is well known 
that coffee produces a peculiar muddiness of complex- 
ion. Tea also stains the skin, and opium destroys its 
natural life and vigor, so that the practised eye dis- 
covers the morphia slave at once by his dead and ex- 
pressionless countenance. 

295. Hygiene of the Kidneys. — These organs are 
in close sympathy with the skin. Whatever causes in- 
activity of the skin imposes extra labor upon the kid- 
neys and renders them liable to disease ; and whatever 
encourages the action of the skin lightens the labor of 
the kidneys. Sedentary habits, neglect of the bath, ex- 
posure to severe cold, the use of irritating condiments, 
excessive use of flesh food, and, above all, the use of al- 
coholic liquors, may be mentioned as the chief causes of 
kidney diseases, which are increasing in this country at 
an alarming rate. 

296. Effects of Alcohol on the Kidneys. — Strong 
.liquors affect the kidneys, as they do the liver and all 



166 SECOND BOOK IN PHYSIOLOGY. 

other parts of the body with which they come in direct 
contact. Degenerations and inflammations are set up, 
which finally result in the destruction of these important 
organs and of life. Kidney diseases which result from 
the use of alcoholic liquors are the most hopeless of all 
maladies of this class. The effect of beer in exciting the 
kidneys to excessive action is well known. The extra 
labor thrown upon the kidneys by the free use of ale 
and beer is a common cause of Bright's disease, one 
form of which is more frequent among beer-drinkers 
than among any other class of persons. The evidence 
of kidney disease may often be seen in the bloated and 
dropsical appearance of habitual drinkers. Those who 
call themselves moderate drinkers do not escape this 
part of the penalty which nature inflicts upon those 
who gratify the appetite for alcohol regardless of the 
possible consequences. 

A part of the work of the kidneys is to remove from 
the blood poisonous substances which are produced in 
the stomach and intestines as the result of indigestion, 
and to carry out of the system food substances which 
have been taken into the blood without being perfectly 
digested. The liver completes the work of digestion. 
When it becomes so disabled from the use of alcohol 
that it cannot do its delicate work efficiently, some por- 
tions of the food are allowed to pass into the general 
circulation without having been so changed by the liver 
as to make them serviceable in building up the body 
or supplying its wants. These unusable substances the 
kidneys are compelled to remove, so far as they are able 
to do so. This is a great addition to their usual work. 

We see, then, that when a person uses alcoholic drinks 
the mischief wrought by the poison multiplies itself. 



HYGIENE OF THE SKIN AND THE KIDNEYS. L67 

1. The alcohol renders the stomach unable to digest the 
food properly, and consequently extra work is imposed 
upon the liver. 2. It impairs the ability of the liver to 
perform its ordinary duties, besides putting upon it the 
double labor of endeavoring to complete the imperfect 
work done by the stomach, and to remove the alcohol. 
3. The kidneys are not only disabled by the alcohol, but 
are compelled to remove a portion of it from the body, 
and also the poisonous and unusable substances resulting 
from the injury to the stomach and the liver. This same 
principle prevails throughout the body. One evil result- 
ing from alcohol creates another, and so the mischief is 
multiplied. 

2 ( J7. Tobacco and Kidney Disease. — Eecent scien- 
tific observations go to show that the use of tobacco is 
a frequent cause of serious disease of the kidneys. A 
very grave malady, known as " Bright's disease " of the 
kidneys, has been traced to the use of tobacco. It is 
more than probable that the mischief done by this ex- 
ceedingly poisonous drug is yet very imperfectly known. 
Its use is so general that the evils resulting from it are 
very easily overlooked, or are ascribed to some other 
cause than the right one. As a large part of the poison 
is carried off through the kidneys, it is inevitable that 
they should suffer in a special manner from its influence. 

It is a common thing to find in smokers a condition 
in which the odor of tobacco " hangs on the breath " ; 
that is, the penetrating odor of nicotine is always pres- 
ent, although the individual may have abstained from 
smoking several hours or even several days. This con- 
dition is due to the fact that the kidneys have become 
diseased, so that they are unable to remove the nicotine 
from the system as fast as it is taken in, and hence it 



168 SECOND BOOK IN PHYSIOLOGY. 

accumulates in the system, saturating every organ, every 
cell, every nerve fibre, the blood, and all the vital fluids. 
A person who is thus saturated with a violent poison is 
certainly not in a fit condition to realize whether or not 
he is suffering from its effects. His benumbed sensi- 
bilities give no warning of the mischief which is being 
wrought in his system, and the danger which threatens 
life as well as health. 

298. Harmful Drugs. — Many of the various drugs 
administered for the cure of disease are removed from 
the body by the kidneys. Some of these, when used for 
a considerable time, produce serious disease of the kid- 
neys. Many of the patent medicines with which so 
many persons dose themselves almost continually, and 
especially the long list of liver and kidney " regulators," 
" cures," etc., are exceedingly harmful to these organs. 
Most of those w r ho take patent medicines for kidney 
disease have no disease of the sort, until disease is pro- 
duced by the drugs which they swallow. 

SUMMARY. 

1. The conditions most essential for the health of the skin are proper 
clothing and cleanliness. 

2. Cosmetics are harmful and sometimes dangerous. 

3. The hair should be kept healthy by cleanliness of the scalp and 
daily brushing. 

4. " Muddiness " of the skin is generally due to bad air and bad diet. 

5. Alcohol, tobacco, and most other narcotics injure the health of 
the skin and destroy its beauty. 

6. Neglect of the bath, the use of irritating condiments, excessive 
use of flesh food, and exposure to cold cause disease of the kidneys. 

7. The use of alcoholic liquors and tobacco causes Bright's disease 
of the kidneys. 

8. The use of ' ' kidney medicines " is unwise, and even dangerous. 



CHAPTER XXI. 
BATIIIXG. 

290. Necessity for Bathing. — More than two mill- 
ion sweat glands are constantly pouring out upon the 
surface of the body a stream of waste matter in solu- 
tion, which amounts to a considerable quantity in the 
course of a day. The watery portion evaporates, leav- 
ing a thin scale of organic filth over the whole surface 
of the body. At the same time millions of little cells 
which compose the cuticle lose their vitality, and are 
replaced by younger ones pressing up from beneath. 
The secretion of the oil glands, dust, and other impuri- 
ties added to the substances deposited from the sweat, 
form upon the skin, even within so short a time as twen- 
ty-four hours, a layer of impurities which needs to be 
removed. 

300. Effects of Water upon the Skin.— When cool 
or cold water is applied to the skin, the blood-vessels 
contract, but quickly relax, causing an increased circu- 
lation of blood in the skin, or a " reaction." If a person 
remains too long in a cold bath this reaction does not 
occur, or is overcome, and the sensation of chilliness 
lasts a long time. Prolonged cold bathing is rarely 
useful. It is often very harmful, and may even be dan- 
gerous. The effect of a hot bath is to relax the blood- 
vessels and to induce sweating. Heat stimulates the 
sweat glands and causes profuse perspiration. The heart 



170 SECOND BOOK IN PHYSIOLOGY. 

also beats stronger and more rapidly, so that the brain 
becomes congested. Very hot baths are rarely useful 
and may do much mischief. 

301. Proper Temperature of Baths. —Water which 
will cause the appearance of goose-flesh when the arm 
is held in it for a moment is cold. That which is near 
the temperature of the body is warm. That which is 
above the bodily temperature is hot. Warm baths should 
not be taken too frequently. A cool bath ma}^ be taken 
two or three times a week with advantage. 

302. How to Bathe. — It would be unnecessary to 
instruct an East Indian how to bathe, for he practises 
the art every day of his life almost from earliest infancy ; 
but among most civilized nations bathing is practised far 
less frequently than it should be. A sponge and towel, 
with two or three quarts of water, are the essentials for 
a simple sponge or towel bath. Begin by washing the 
face and neck and wetting the top of the head. Next 
apply the wet sponge to the chest, arms, and shoulders, 
then to the rest of the trunk, and lastly to the legs and 
feet. Rub a little soap into the armpits and all the 
creases of the body before applying the water. Have a 
large dry sheet or one or two towels in readiness. Dry 
quickly, and then rub the skin with a coarse towel, a soft 
flesh-brush, or a bath-mitten, until it glows ; then dress 
and exercise for a few minutes. If the room is cool, 
or if the person chills easily, he should bathe only a 
small portion of the body at a time, drying the part 
bathed before wetting another. 

303. The Full Bath.— This bath is taken in a tub of 
sufficient size to allow the whole body to be immersed, 
with the exception of the head. A little soap should be 
used. The general tendency is to take such baths too 



BATHING. 171 

warm. The temperature of the water should not be 
over 00° to 98° Fahr. After such a bath, especially in 
damp or cold weather, a little fine oil, as olive or cocoa- 
nut oil, should be applied to the skin to replace the nat- 
ural covering of oil. This is especially important when 
a warm bath lias been taken for the relief of a cold. 

304. Rules for Bathing. — The following rules are 
important: 

1. Do not bathe just before or soon after eating. 

2. Be careful to dry the skin thoroughly, not neglect- 
ing the feet, before dressing. 

3. Exercise vigorously after a cold bath. Eest after a 
warm bath. 

4. Never take a cold bath when exhausted or when 
perspiring. 

5. If giddy or faint in a bath, leave it at once, lie 
down, sip cold water, and apply cold water to the face 
and the head. 

SUMMARY. 

1. Frequent bathing is made necessary by the accumulation of waste 
matter, dead cells, oil, and foreign substances upon the surface of the 
body. 

2. Water not only cleanses the skin, but stimulates the circulation of 
blood through it. 

3. The beneficial effects of cool bathing are due to the reaction pro- 
duced. 

4.* Cold bathing is seldom beneficial and often does harm. 

5. Very hot baths are sometimes unsafe, and are seldom needed. 

6. Baths should be taken with careful regard to proper rules. 



CHAPTER XXII. 
CLOTHING. 

305. What to Wear for Health. — The materials 
usually worn in clothing are linen, cotton, silk, and wool, 
to which must be added leather for shoes and rubber for 
over-shoes and over-garments. 

Linen has the advantage of being smooth, soft, and 
light, but is an inferior material for clothing, particu- 
larly for under-garments. A linen garment feels cold 
and wet when in the least degree moist. Cotton is a 
better material for clothing to be worn next the skin, 
especially in warm weather. Silk is still better, but wool 
is best of all (Experiment 16, page 275). The only objec- 
tion to wool is that it is sometimes irritating to the skin, 
and so cannot be worn with comfort. In such cases a 
thin cotton or silk garment may be worn under the wool- 
len. Rubbers and mackintosh coats retain the perspira- 
tion in the clothing, on which account care should be 
taken to change or dry the clothing after wearing rub- 
ber protectors for any length of time (Experiment 17, 
page 275). 

306. Clothing should be Adapted to the Season 
and Weather. — More clothing is of course necessary 
in winter than in summer, but the amount of clothing 
required varies less than the temperature. 

In man, as well as in lower animals, the system under- 
goes a change with each season of the year, by which it 



CLOTHING. 173 

adapts itself to new conditions. This change produces 
what is termed the " winter constitution " in winter, and 
the "summer constitution" in summer. The "winter 
constitution" is well adapted to resist cold, while the 
" summer constitution " is prepared to resist heat ; con- 
sequently, conditions the reverse of those for which the 
body is prepared are severely felt. 

On this account we need more clothing in summer 
than in winter, even when the temperature of the air is 
the same. 

The fashion of putting off and putting on winter or 
summer clothing at certain dates, as is customary with 
many persons, is a mischievous one. A change from 
warm to cold weather, or the reverse, at any season of 
the year, should, always be met by a corresponding 
change in clothing. The outer garments may remain 
the same, but the under-garments should be modified 
from day to day as the weather may indicate. Observ- 
ance of this rule will amply repay the necessary trouble 
in the saving of sickness and consequent expense and 
loss of time. 

307. Clothing of the Feet, — Many persons permit 
their feet and limbs to be so thinly clad in cold weather 
that they are never properly warm. In children their 
development is checked, and a large part of the blood 
which the feet and limbs should contain is crowded into 
the head and other organs, which already have a full 
supply, thus doing double mischief. Young children 
and aged people require more clothing than adults. 

Tight shoes or boots prevent the proper circulation of 
the blood in the feet, and produce corns, bunions, swell- 
ings, and sometimes still more serious diseases of the 
feet. High heels throw the weight of the body too 



174 SECOND BOOK IN PHYSIOLOGY. 

much forward, and French heels, which are set forward 
under the foot, transfer the weight to the hollow of the 
foot, which is not at all fitted to bear w x eight. The wear- 
ing of such shoes breaks down the instep, producing the 
condition known as " flat-foot," and renders a graceful 
carriage of the body impossible. The stockings should 
be held in place by supporters, and not by tight elastics 
(Experiment 18, page 276). 

308. Clothing of the Neck and the Head.— Colds 
and sore throats most often result from exposure of the 
head and throat. If the head and the throat were never 
covered they would learn to take care of themselves, as 
does the face ; but when covered most of the time, and 
then occasionally exposed, colds are easily contracted. 
Coverings for the head and the throat should be suffi- 
cient for comfort in cold weather, but not so warm as to 
cause perspiration, as this will insure taking cold. Ex- 
tra wrappings about the throat should be worn only 
when required by reason of unusual exposure. 

309. Evils of Tight Lacing. — Proper breathing re- 
quires unrestrained action of the muscles of the chest 
and abdomen. If the waist is compressed by tight cloth- 
ing the breathing is seriously interfered with, and not 
only are the lungs thereby rendered liable to disease, 
but the whole body suffers from the insufficient supply 
of air. Oxygen is needed to cleanse the tissues, and it 
is no winder that the young lady who foolishly laces 
her clothing tightly, under the mistaken notion that 
beauty demands a small round w r aist for a good figure, 
loses her clear, rosy complexion, and becomes pale and 
sallow. 

Pressure upon the waist also does great mischief by 
displacing internal organs. The liver and the stomach 



CLOTHING. 175 

are often crowded out of position, and so cruelly com- 
pressed that they become permanently deformed. Phy- 
sicians often meet cases in which examination shows the 
liver to be nearly cut in two by this outrageous viola- 
tion of nature's laws. Under such circumstances, it is of 
course impossible that the stomach and the liver should 
be able to do their work properly. (Figs. 30 and 31.) 

The fashionable Chinese mother bandages the feet of 
her little girls in such a manner as to dwarf their 
growth and produce almost incredible deformity. The 
process is accompanied by very great pain, but is in- 
sisted upon for the purpose of conforming to the absurd 
custom which demands that the foot of an aristocratic 
Chinese woman shall be simply a rounded stump, so 
that it may be squeezed into a very small shoe. The 
author once measured a shoe worn by a Chinese lady, 
and found it to be exactly three inches in length. Ri- 
diculous as this custom is, it is no more worthy of con- 
demnation than the wearing of tight, high-heeled French 
shoes, so commonly worn at the present day by fashion- 
able women in civilized lands. 

310. Tight Lacing and Gall-stones. — Women suf- 
fer from gall-stones and jaundice very much more fre- 
quently than do men, which is doubtless due to the fact 
that compression of the waist involves direct pressure 
upon the liver, and restrains the action of the diaphragm. 
In consequence, the liver and gall-bladder are not w 7 ell 
emptied of bile, and the secretion becomes hardened into 
masses termed gall-stones. Women and girls, as well as 
men and boys, should wear their clothing so loose that 
the low T er part of the chest can be fully expanded. 

311. Change of Clothing. — The clothing, especially 
that worn next the skin, absorbs a large amount of the 



176 



SECOND BOOK IN PHYSIOLOGY. 



waste matters thrown off by the skin, and so becomes 
charged with impurities. On this account the under- 
clothing should be changed not less often than once a 



/ 



A%, 



n *''"'///g/// 



\ 







Fig. 30. — Natural Form. 



week in winter. In the summer season, and whenever 
the skin is unusually active, health will be promoted by 
a daily change. In cold weather the comfort of the feet, 



CLOTHING. 



177 



if they are inclined to be cold, will be greatly promoted 
by a daily change of the stockings. 

31 2. Night Clothing. —The clothing worn during the 



J 



V 







Fig. 3i — The Results of Uniiealthful Dress. 



night should exclude every article worn during the day. 
In winter-time a long woollen bed-gown, is as necessary 
for health as for comfort. When the feet and extremities 
are cold, woollen bed-socks should be worn in addition. 



178 SECOND BOOK IN PHYSIOLOGY. 

313. Beds. — The bedclothing should be dry and warm. 
A cold bed is necessarily a damp bed, as it condenses 
moisture from the body of the sleeper, as well as from 
the air of the room. A damp bed becomes musty. A 
person sleeping in such a bed is not only debilitated by 
the loss of animal heat, but is poisoned by the inhala- 
tion of musty, germ-laden air, which he is compelled to 
breathe during at least a third of the twenty-four hours. 

Bedclothing should be of porous material, so that the 
exhalations from the skin may not be retained in contact 
with the body, to be reabsorbed. Feather-beds absorb 
so readily and retain so tenaciously the exhalations of 
the body that they are justly regarded as objectionable. 
Bed-covers and mattresses should be thoroughly aired 
daily, and should be exposed to the direct rays of the 
sun when possible, or dried before a fire. 

A sleeping-room should always contain a heater, un- 
less warmed by a furnace or from an adjoining and 
communicating room. A grate is the most healthful 
mode of heating a sleeping-room. The bedroom should 
not be too warm, but should be heated sufficiently each 
day to insure diyness. Sleeping in a room which is too 
warm is enervating and unrefreshing. The temperature 
of a sleeping-room for healthy persons should be little 
above 50° F. Infants and aged persons require a higher 
temperature, as do also feeble invalids. 

314. Poisonous Colors. — Numerous cases have oc- 
curred in which serious illness, accompanied by painful 
inflammation of the skin, has arisen from wearing arti- 
cles of clothing colored with poisonous dyes. Flannel 
under -garments, stockings, and colored hat -bands are 
the most frequent means of communicating the poison. 
Red and other aniline colors are most likely to be 



clothing. IT:) 

poisonous. New stockings and under-garments, if col- 
ored, should be well washed before they are worn. 

SUMMARY. 

1. The materials used for clothing are valuable, from a health stand- 
point, in the oider named : wool, silk, cotton, linen. 

2. The clothing should be adapted to the season of the year, and to 
changes in the weather at all seasons. 

3. The clothing should be so arranged as to secure equable warmth 
Infants and aged persons require extra warmth. 

4. The clothing should be so adjusted as to allow perfect freedom 
of movement in all parts of the body. 

5. Shoes with narrow toes, and high or French heels, produce serious 
disease of the feet and other organs. 

6. Clothing worn during the day should net be worn at night. 

7. Bedclothing should be aired, and, if possible, exposed to the sun 
daily. 

8. Impervious material should be worn only a few hours at a time, 
and should not be used as bedclothing. 

9. Eruptions and inflammation of the skin are sometimes produced 
by clothing colored with poisonous dyes. 



CHAPTER XXIII. 

THE BOXES : THEIR USES, AND HOW TO CARE FOR 

THEM. 

The framework of the body, the skeleton, supports 
the various structures and organs. The simplest form 
of a skeleton is nothing more than a stony or horny 
framework over which a soft animal substance is spread. 
The common sponge is a skeleton of this sort. 

315. The Structure of Bones. — The human skele- 
ton is a much more complicated and perfect structure. It 
consists of many different parts, each wonderfully suited 
to its use. There are three sorts of structures found in 
the skeleton — hones, cartilages, and ligaments. 

The bones are the hardest tissues in the body. Bones 
are covered by a tough membrane known as periosteum. 
The periosteum sends into the bone numerous blood-ves- 
sels and a few nerves, through which the bone is de- 
veloped and nourished. 

Experiments made for the purpose of determining the 
strength of solid bony tissue show that it will resist 
greater pressure than the strongest oak. 

Long cylindrical bones, like the bones of the thigh, 
are hollow, and the interior is lined with a membrane 
similar to that which covers the surface. The cavities 
of hollow bones are filled with a substance chiefly com- 
posed of fat and blood-vessels, the marrow. 

The large bones of the arms and legs are long bones 



THE BONES: THEIR USES AM) CAKE. 181 

The ribs and the bones of the upper part of the skull 
are flat bones. The little bones of the wrist arc short 
bones. Most of the bones of the face 
are irregular bones. ^^ 

310. Cartilage. — This is a tough, 
elastic substance, which composes the 
greater portion of the bones in early life. 
As we grow older, the cartilage for the 
most part hardens into bone. 

317. The Joints. — The points at 
which bones join are termed joints. 
There are in the human skeleton many 
joints, most of which are movable. Some 
joints move with very great freedom, as 
the shoulder ; others have less motion, 
as the elbow ; and still others have no 
motion. The structures of a movable 
joint are : 1. The cartilages, which cover 
the ends of the bones forming the joint. Ficr g2 _ Sect10N 
2. The ligaments, which bind the parts of a Long Bone. 
of the joints firmly together. 3. A deli- 
cate membrane which encloses the joint called the syno- 
vial membrane. This membrane secretes a limpid fluid 
by which the joint is lubricated, the synovial fluid. 

There are several kinds of movable joints, as the hinge- 
joint, of which the elbow and the finger joints are ex- 
amples, the ball-and-socket joint, as seen in the shoulder, 
and joints in which two flat surfaces glide over each 
other, as in the bones of the wrist. 

318. The Skeleton. — The entire skeleton consists of 
just two hundred bones, twenty-two of which are found 
in the head, fifty-two in the trunk, sixty-four in the up- 
per extremities, and sixty-two in the lower extremities. 



182 SECOND BOOK IN PHYSIOLOGY. 

319. Bones of the Skull and Face.— Eight of the 
bones of the head are united in such a manner as to 
form a hollow case called the skull, in which the brain 
is safely lodged. The form and structure of the skull 
are such as to afford the greatest amount of strength and 
protection with the least weight of material. The skull 
presents a number of small openings for the passage of 
nerves and blood-vessels, and at the lower back part is a 
very large opening through which the spinal cord passes 
to join the brain. Fourteen of the bones of the head 
belong to the face. Two of these form the bridge of 
the nose, two the prominent parts of the cheek, two the 
upper jaw, one the bony partition of the nasal cavity, 
and one the lower jaw. The others line the cavities of 
the nose and mouth. The two jaw bones contain sockets 
for the teeth. 

It sometimes occurs, in the development of the body, 
that the bones or soft tissues of the upper jaw fail to 
unite completely, leaving a deficiency which is known 
as " hare-lip." 

320. The Bones of the Trunk consist of the fol- 
lowing : Twenty-four vertebral, which compose the back- 
bone ; an equal number of ribs ; the sacrum, a bone of 
peculiar shape, which joins the lower end of the spine ; 
the coccyx, a small bone added to the lower end of the 
sacrum; the breastbone or sternum; and the hyoid bone, 
a small bony ring which is placed just under the lower 
jaw, and supports the root of the tongue. The form 
and position of each of the principal bones is shown in 
Figure 33. 

321. The Spinal Column. — This remarkable bony 
structure is so made that it may bend with ease in any 
direction with the movements of the trunk of the body, 






THE BONES: THEIR USES AM) CARE. 



183 



and without occasion- 
ing inconvenience to 
the delicate parts 
which it protects. 
This wonderful result 
is accomplished by 
the arrangement of 
a number of separate 
bones, one above an- 
other, each of which is 
called&vertebra. Each 
vertebra has a thick 
portion called its 
body, a ring-shaped 
portion, and several 
projections. The lat- 
ter are for the attach- 
ment of the ribs and 
the ligaments by 
which the several ver- 
tebras are held to- 
gether. When ar- 
ranged one above an- 
other, with the bodies 
and rings of each in 
corresponding posi- 
tions, a bony column 
is formed with a canal 
extending through its 
entire length. This is 
called the spinal col- 
umn. 

The upper vertebrae are so peculiarly shaped as to 




Fig. 33. — Thk Skeleton. 



184 SECOND BOOK IN PHYSIOLOGY. 

enable the head to " nod," and to be turned from side to 
side. By the combination of these two movements the 
head may be turned in every direction. The vertebrae 
are separated from each other by means of disks com- 
posed of very elastic cartilage. 

In consequence of this arrangement of the spinal col- 
umn, a person who is much on his feet becomes shorter 
during the day, through thinning of the cartilages be- 
tween the vertebrae, and regains his height during the 
night. Most persons are half an inch taller in the morn- 
ing than at night. 

322. The Ribs. — These bones connect the spinal 
column with the sternum. The first seven are called 
true ribs, because they are connected with the breast- 
bone, each by a separate cartilage. Of the remaining 
five, known as false ribs, three are joined to one cartilage, 
which connects them to the sternum, and two are left un- 
connected. These latter are termed floating ribs. 

323. The Thorax. — The spine, the ribs, the sternum, 
and the diaphragm enclose a cavity which is called the 
thorax. This cavity contains the heart, the lungs, large 
blood-vessels, and other important organs. 

321. The Pelvis. — This is the name given to the 
cavity enclosed between the sacrum and the coccyx and 
the two large bones which form the hips. The pelvis 
contains the bladder and other important organs. 

325. The Upper Extremity, or Arm, consists of 
the following bones : The shoulder-blade, or scapula; the 
collar-bone, or clavicle ; the upper-arm bone, or humerus ; 
the two bones of the fore-arm — radius and ulna; the 
eight bones of the wrist ; and the nineteen bones of the 
hand. 

326. The Lower Extremity consists of the hip- 



THE BONES: THEIR USES ANM) CARE. 



185 



bone ; the thigh-bone, or femur ; two leg-bones — tibia and 
fibula; the knee-cap, or patella ; seven anlde -bones ; 
and the nineteen bones of the /cx^. 

The bones of the foot are so arranged as to form an 
arch, the instep, which adds greatly to the strength and 
beauty of the foot. When this arch becomes broken 
down, as it sometimes does from wearing ill-fitting shoes 
or boots, a person becomes flat-footed, and cannot walk 
far without great fatigue and discomfort. 

327. Composition of the Bones. — The remarkable 
firmness and solidity of bony structures is due to the 
large amount of organized salts w T hich they contain. 
When burned, a bone is found to lose one -third its 
weight, though retaining its form. This 
shows that only about one-third of its 
weight is animal matter. The remaining 
two-thirds consists chiefly of phosphate 
of lime, which constitutes more than one- 
half the entire Aveight of the bone. About 
one-ninth of the weight of the bone con- 
sists of carbonate of lime, or chalk. Of 
course there is neither phosphate of lime 
nor chalk in living bone. These elements 
are found after the bone has been burned, 
being formed out of the organized salts 
which exist in the living bone (Experi- 
ment 19, page 276). 

If a fresh bone is placed for a few 
days in a dilute acid, the earthy matter 
will be dissolved out. It will then be 
found that the bone has lost two-thirds 
of its weight, and that the portion remaining, wiiile of 
the same form as before, will have lost its firmness, and 




Fig. 34.— BoxeDe- 

priyed of Earthy 

Matter. 



186 SECOND BOOK IN PHYSIOLOGY. 

become so flexible that if the bone is long and slender, 
as a rib of a sheep, it may easily be tied in a knot. The 
portion left constitutes the animal matter of the bone 
and consists chiefly of gelatine. 

328. The Bones in Infancy and Old Age.— From 
infancy to old age the bones acquire an increasing 
amount of earthy matter. On this account the bones 
are more brittle in old age, and less easily broken in 
infancy and childhood. 

329. Uses of the Bones. — The chief uses of the 
bones are : 1. To support the soft parts of the body. 
2. To protect delicate and sensitive parts. 3. In connec- 
tion with the muscles, to move the body and its various 
parts. On each bone is found raised or roughened 
places, ridges, etc., to which, in life, muscles are at- 
tached. By the connection of the muscles with the 
bones, the latter are used as levers to do the work of 
the body and to move it about. 4. Recent discoveries 
have shown that the red marrow of the bones is active 
in producing blood corpuscles. 

SUMMARY. 

1. The skeleton is composed of bones, cartilages, and ligaments. 

2. The general divisions of the skeleton are: Head, 22 bones; trunk, 
52; upper limbs, 64; lower limbs, 62. 

3. The head comprises — skull, 8 bones; face, 14. 

4. The trunk comprises — vertebrae, 24 bones; ribs, 24; sternum, hy- 
oid, sacrum, and coccyx. 

5. Each upper limb comprises — scapula, clavicle, humerus, ulna, 
radius, 8 bones of the wrist, and 19 bones of the hand. 

6. Each lower limb comprises — hip, femur, tibia, fibula, patella, 7 
bones of the ankle, 19 bones of the foot. 

7. The joints are formed by bones, cartilages, ligaments, synovial 
membrane, and are lubricated by synovial fluid. 

8. The bones constitute a framework for the body, protect delicate 
parts, and serve as levers. The red marrow makes red corpuscles. 



CHAPTER XXIV. 
HYGIENE OF THE BONES. 

In order that they may be properly developed, the 
bones must be supplied with food containing an abun- 
dance of " salts," the kind of nutrient elements which 
they especially require. These are found in their best 
form in milk and in whole-grain preparations. Rickets, 
a disease in which the bones are affected so seriously 
that great deformit} r often results, is very probably due, 
in part at least, to a lack of this element in the food. 

Exercise should be carefully adapted to a person's 
age and development. The flexible bones of young 
children sometimes become seriously bent, as in cases 
of " bow-leg " and " bandy-leg " — deformities which are 
the result of allowing an infant to walk before its bones 
are sufficiently firm to support the weight of the body 
without bending. Exercise is necessary for the proper 
development of the bones. 

Spinal curvatures, round shoulders, flat chest, and 
other deformities result from sitting in improper posi- 
tions, a habit usually formed at school. This is a mat- 
ter to which teachers and parents should give attention, 
as the mischief done in early years can seldom be whol- 
ly corrected by the most skilful treatment afterwards. 
The deformities of the trunk and the feet which result 
from improper dress have been elsewhere considered. 

330. Injuries of the Bones and the Joints. — 



188 SECOND BOOK IN PHYSIOLOGY. 

When a bone is broken, the muscles often draw the ends 
of the bone apart, so that a skilled physician is required 
to put them in proper position. After being " set," they 
must be retained in position by splints and bandages until 
nature has time to cement the parts together by means of 
a substance produced between and around the ends of the 
broken bone. This cement substance gradually hard- 
ens, and after a time becomes as firm as bone, and makes 
the bone nearly as good as before. 

In consequence of a blow or a fall, the end of a bone 
is sometimes dislocated, or "put out of joint." In some 
cases the displaced bone may be readily restored to its 
proper position, but often this can be done only with 
great difficulty. On the occurrence of such an accident 
a skilful surgeon should be called at once. 

A sprain is an injury due to a strain of a joint by a 
misstep or otherwise, as the result of which a ligament 
is lacerated or torn from its fastenings to the bone. A 
bad sprain may be more serious than a fracture. A 
bunion is a painful swelling over a joint, caused by irri- 
tation of the synovial membrane, which is usually due 
to the pressure of a tight or badly fitting boot or shoe. 

331. Alcohol and Tobacco. — The effect of these 
1 poisons in preventing the proper development of the 
bones is so apparent that even those who defend their 
use by adults do not hesitate to condemn their use by 
those who have not yet attained maturity. A boy who 
early begins to smoke cigars or cigarettes, or to use alco- 
holic drinks, is very likely to be dwarfed in body and 
mind. Even the bones, in some cases, will not develop 
properly. Doubtless, grown persons who use tobacco 
suffer equally, though differently. The effect of alcohol 
or tobacco upon a boy is to check his growth ; upon a 



HYGIENE OF THE BONES. 189 

man, to shorten his life. The effects upon grown per- 
sons, though sometimes less apparent, are none the less 
positive. Certainly the character of these poisons is not 
changed by the age of the person who uses them. 

The important function of the red marrow of the 
bones in producing blood corpuscles must be seriously 
interfered with by the poisonous influence of alcohol and 
tobacco. The peculiar pallor of smokers and chronic 
drinkers is perhaps due in large part to this poisonous 
effect of these injurious agents. Any agent which par- 
alyzes the blood-making organs of the body, or im- 
pairs their activity, must be most destructive to life and 
health. As has been elsewhere shown in this work, 
alcohol and tobacco are poisons, and destructive to all 
living cells, whether animal or vegetable. When these 
poisons are circulated in the blood, their injurious influ- 
ence is exerted upon every cell and tissue in the body. 
Their influence upon other blood-making organs, as well 
as the red marrow of the bones, must be in the highest 
degree detrimental to health and vigor. 

SUMMARY. 

1. Bones require for their development food containing an abun- 
dance of "salts." which are especially found in whole-grain prepara- 
tions. 

2. Exercise must be adapted to the age and to the stage of develop- 
ment. 

3. Deformities of the bones often result from improper positions, 
especially in sitting at school. 

4. The use of alcohol and tobacco by young persons prevents the 
proper development of the bones, as well as the growth of other parts 
of the body. 



CHAPTER XXV. 
ANATOMY AND PHYSIOLOGY OF THE MUSCLES. 



332. Muscular Fibres. — A muscle is chiefly compos- 
ed of minute fibres, each of which possesses in a remark- 
able degree the property of contractility. A piece of 
lean corned-beef, when boiled, may be easily separated 
into small bundles. These bundles may, by the use of 

needles, be "teased" out into fine 
fibres, which, under a small magnify- 
ing-glass, may be separated into fibres 
still smaller. These last minute threads 
of animal substance are the muscu- 
lar fibres. (Fig. 35.) The fibres of a 
muscle are held together by a sheath 
of connective tissue. 

The total number of separate mus- 
cles in the body is about five hundred. 
The muscles vary in size from a cer- 
tain muscle in the leg, which in a tall 
man is nearly two feet in length, to 
the delicate little muscles of the ear, 
to see which one almost requires a 
magnifying-glass. The muscles con- 
stitute that portion of the body which in lower animals 
is commonly known as lean meat. 

333. Tendons. — In its ordinary form a muscle con- 
sists of a fleshy central portion, the muscle proper, joined 




Fio 



35. — Muscular 
Fibre. 



ANATOMY AND PHYSIOLOGY OF THE MUSCLES 1 ( .)1 

at each end to a white cord-like structure, chiefly com- 
posed of white fibrous tissue, and known as tendon. By 
means of the tendons the muscles are firmly attached 
to the bones. Each muscle has usually two points of 
attachment. The one which is least movable, or which 
is nearest the centre of the body, is termed the origin ; 
the other, the insertion. Some muscles have tendons at 
each end, others at the point of insertion only, while still 
others have none at all. 

334. Forms of Muscles. — Some muscles are shaped 
like a spindle ; others like a feather ; still others are 
spread out like a fan, and a few have the form of a 
ring. These structures adapt themselves in a most in- 
teresting manner to the varying needs of the body. 

335. Two Classes of Muscles. — Besides the mus- 
cles which chiefly constitute the fleshy portion of the 
body, and which we are able to use at will, there are 
muscles of a very distinct class, mostly found in the in- 
terior of the body, which act according to the needs of 
the body, and quite independent of the will. The walls 
of the hollow organs — the stomach, intestines, bladder, 
and blood vessels — are in part made up of this kind of 
muscular tissue. Those muscles which are controlled by 
the will are termed voluntary muscles ; those not under 
control of the will are called involuntary muscles. 

Those muscles which are not under the control of the 
will have a structure very different from that of volun- 
tary muscles. When examined with a microscope, they 
are found to consist of spindle-shaped cells closely inter- 
woven. The muscle tissue of the heart is of a mixed 
character, resembling both voluntary and involuntary 
muscular tissue. 

336. The Muscles of the Face. — The upper part of 



192 SECOND BOOK IN PHYSIOLOGY. 

the skull is covered by two muscles, one on each side, ex- 
tending from the eyebrows to the back part of the head. 
By contracting this muscle we wrinkle the skin of the 
forehead. Other little muscles, attached to the skin of 
the forehead in different positions, enable us to elevate 
the eyebrows, as when we look surprised, or to draw 
them down, as in scowling. The nose is furnished with 
muscles which enlarge and contract the nostrils. Sev- 
eral powerful muscles connect the lower jaw with the 
upper, and also with the skull, by means of which we 
are able to open and close the mouth in speaking and 
in eating, as well as in various expressions. 

337. Muscles of Expression. — A large circular 
muscle surrounds the mouth, enabling us to contract it, 
as in puckering the lips. Attached to- this circular mus- 
cle are little muscles running off to various parts of the 
bones and skin of the face. Some draw the corners of 
the mouth up, and others draw them down. Some ele- 
vate the lips, others depress them. These various mus- 
cles, acting with other muscles of the face, give to the 
countenance its wonderful and ever- varying expression. 
Every emotion of the mind has thus its shadow in the 
face. It is evident that if a certain class of thoughts is 
constantly affecting the face so as to make its muscles 
contract habitually in a particular way, the face will 
after a time retain permanently the expression given to 
it by the action of these muscles. It is thus that the 
face becomes an index to the character. The proper 
training of the muscles of the face is an important part 
of one's education. 

338. Muscles of the Trunk. — The muscles of the 
trunk are very numerous, and are arranged in layers. 
Those of the upper part assist in inspiration. Those of 



ANATOMY AND PHYSIOLOGY OF THE MUSCLES. L93 

the lower part aid expiration, enclose the abdominal cav- 
ity, and, acting with the muscles of the back, hold the 
body erect, and execute most of the movements of which 
the trunk is capable. The muscle which forms the par- 
tition between the cavity of the chest and that of the 
abdomen is called the diaphragm. It is the most impor- 
tant muscle of respiration. 

339. Muscles of the Arm. — The arm muscles are 
fifty-eight in number. The upper arm is acted upon by 
eleven muscles, some of which connect the arm with the 
trunk ; others connect the upper arm with the fore-arm. 
The largest of these are the pectoral, which forms the 
fleshy part of the chest, the biceps, which forms the 
front part of the upper arm, and the triceps, which 
forms the back part of the upper arm. These muscles 
give to the arm a great variety of movements. The 
fore -arm has four principal movements: bending, or 
flexion; unbending, or extension; turning inward so as 
to bring the palm of the hand downward, or pronation; 
and turning outward, or supination. These movements 
are accomplished by thirteen muscles. The wrist joint 
is controlled by sixteen different muscles, which give to 
it great freedom and variety of movement. The mus- 
cles of the thumb and fingers are eighteen in number, 
and enable these organs to execute a great number of 
movements. 

310. Muscles of the Lower Extremity. — The 
thigh is moved by twenty distinct muscles, most of which 
arise from the trunk. Three of these compose the fleshy 
portion of the hip. The muscles which move the leg 
are ten in number. The largest is the rectus, which 
forms the front of the thigh. One of the most remark- 
able is the sartorius, or tailor's muscle, so called because 



194 SECOND BOOK IN PHYSIOLOGY. 

it is used in crossing the legs under the body as tailors 
often do at their work. It is the longest muscle in the 
body. 

The foot and toes are controlled by twenty muscles, 
the two largest of which form the calf of the leg and 
are joined to the heel by the tendo-achilles. The toes 
move much less freely than the fingers, though in in- 
fants, whose feet have not been cramped by badly fit- 
ting shoes, they are capable of a considerable degree 
of movement. Persons born without hands sometimes 
learn to use the feet and toes in writing and sewing. 

341. How a Muscle Contracts. — The contraction 
of a muscle consists in the shortening of the many fibres 
of which it is composed. In shortening, each fibre thick- 
ens, so that the actual size of the muscle is not materi- 
ally changed. If the tendon of a muscle is cut, the 
muscle at once contracts, which shows that it is alwaj^s 
a little stretched, even when at rest. This is necessary 
to secure steadiness and promptness in muscular move- 
ments. Most movements, as those of the arms and 
legs — even the simple act of standing erect — require 
the harmonious action of many muscles, each of which 
is balanced against some other one, thus enabling us to 
execute steady and graceful movements. 

342. Involuntary Muscular Action. — The action 
of involuntary muscles is not prompt and vigorous as that 
of voluntary muscles. It is slow, rhythmical, and is said 
to be constant in a state of health. The heart muscle 
partakes of the properties of both voluntary and invol- 
untary muscles, to which fact is due its capacity for 
such vigorous and continuous work. 

343. Amount of Work Done by the Muscles.— 
All the perceptible movements of the body are the result 



ANATOMY AND PHYSIOLOGY OF THE MUSCLES. 195 



of muscular action. It has been calculated that the mus- 
cles employed by a common laborer in doing an ordi- 
nary day's work perform an amount of work equivalent 
to lifting 1000 tons. A horse does seven times as much 
work as a man. The most rapid movements possible to 
human muscles are eight or ten a second ; but birds and 
insects make much more rapid movements. 

It has been calculated that, in rowing, an oarsman in 
a well-trained crew does Avork equal to lifting four tons 
one foot high every minute, which in one hour and 
forty minutes amounts to a full day's work for an or- 
dinary laborer. Many creatures smaller than man are 
much more powerful in proportion to their size. A man 
can scarcely leap two or three times his own length, but 
a flea or a grasshopper will leap two or three hundred 
times its length. Imagine a creature with the legs of a 
flea, the wings of a dragon-fly, a pair of jaws and a coat 
of mail like those of a beetle, and magnified to the size 
of an elephant ! Such a creature could leap from the 
north to the south pole at a few bounds, could crush 
the strongest steel in its jaw r s, and resist a cannon-ball 
with its armor. 

314. The Muscles as Machines. — When a man 
uses a crow-bar to pry a stone out of the ground, he em- 
ploys it as a lever. There are several kinds of levers, 




£fc 



Fig. 36 —A Lever. 



196 SECOND BOOK IN PHYSIOLOGY. 

all of which are illustrated in the human body in the ar- 
rangements of the muscles with the bones. The bones 
are the levers, the muscles apply the power, and the vari- 
ous objects moved, the body itself or its parts, are the 
weights lifted. 

345. The Hands. — The human hand, in the great va- 
riety and precision of movements of which it is capable, 
is approached by no similar organ possessed by any other 
animal. Its chief utility arises from the power to op- 
pose the thumb to the fingers. The hand of the ape is 
by no means so perfect as the human hand. By train- 
ing, the hand may acquire a degree of skill and dexterity 
which is truly marvellous. 

346. Use of the Legs. — The many muscles which 
compose the fleshy part of the limbs are, some of them, 
in constant activity except when the body is 

in a reclining position. In standing, many ^tf\v 1 : W]\ 
muscles are constantly active in steadying ■By/^' 
the body and in holding it erect. Walking, H Iffl 
running, and leaping are different modes of « \j jj 
using the limbs in moving from one place A If 
to another. Running differs from walking in §| || 
that the two feet are off the ground at the ftlQ^j 

same time, though one is in advance of ^ ^^ ■■■^^m 

the other. In leaping, the two feet +&^^^ 

are off the ground at once, and are Fig. 37. — action of the 

. ,, Muscles of the Foot in 

together. Walking. 

347. Other Uses of the Mus- 
cles. — The use of muscles in expression, in speaking, 
and in breathing, has already been referred to, as well 
as their connection with the processes of digestion and 
circulation. The muscles are also useful in giving to 
the body symmetry and grace of form and movement, 



ANATOMY AND PHYSIOLOGY OF THE MUSCLES. 197 

covering up the rugged angularities of the bones, and 
rounding out the figure. 

Another important use of the muscles is by their ac- 
tivity to regulate nutrition. The muscles are the chief 
source of bodily heat, and consume the greater part of 
the material which is taken in as food. Any portion 
of food which is not immediately used is stored as re- 
serve tissue. This stored material serves the body as 
does the coal a locomotive. If more food is taken than 
is consumed by the muscles, the reserve tissue will in- 
crease, and obesity will be the result. By regulating 
the amount of exercise proportionately to the amount 
of food taken, the weight of the body may be main- 
tained at an equilibrium. 

348. The Muscular Sense. — It is by means of the 
muscular sense, termed the sense of iveight, that we are 
able to judge of the weight of one object as compared 
with that of another. The muscles possess sensibility 
to pain in less degree than does the skin. 

SUMMARY. 

1. A muscle is composed of minute contractile fibres. 

2. There are in the body about five hundred muscles of various 
forms. 

3. Muscles are joined to bones by tendons. 

4. There are two general classes of muscles, voluntary and involun- 
tary. 

5. Principal groups of muscles: Muscles of the head and the face; 
of expression; of the trunk — hold body erect, enclose abdomen, aid 
respiration; of the arms, 58 in number— upper arm 11, fore-arm 13, 
wrist 16, thumb and fingers 18; of the lower limbs, 50 in number — 
thigh 20, leg 10, foot and toes 20. 

6. Names of some of the principal muscles of the body: Pectoral 
biceps, triceps, diaphragm, rectus, sartorius. 

7. The muscles use the bones as levers. 

8. The muscles are the seat of a special sense, the sense of iceight. 



CHAPTER XXVI. 
HOW TO KEEP THE MUSCLES HEALTHY. 

349. Exercise. — The first condition essential for the 
health of the muscular system is regular and system- 
atic exercise. It is a law of nature that an unused 
organ dwindles away until it becomes quite useless. 
When not in action, a muscle is pale, and receives little 
blood. When active, the supply of blood is greatly in- 
creased. Exercise stimulates growth. The effects of 
exercise are well shown in the arms of the blacksmith 
and the wood -chopper. Their arm muscles are large 
and hard, while those of persons who use the arms but 
little in vigorous exercise, as students, lawyers, editors, 
and most professional men, are thin and soft. 

When not used at all, the muscles become stiff, as 
well as weak and flabby ; that is, they will not read- 
ily respond to the orders sent them by the will. The 
joints also become stiff, so that movement is slow and 
painful, and may become impossible. Regular daily ex- 
ercise keeps the muscles strong and supple, and the joints 
flexible. 

350. Effect of Exercise on other Organs. — Ex- 
ercise is as essential for the health of the body in gen- 
eral as for that of the muscles. The heart and the 
breathing muscles are especially influenced by exercise. 
A person who exercises little gets out of breath easily ; 
while one who is accustomed to rapid walking or run- 



HOW TO KEEP THE MUSCLES HEALTHY. L99 

ning has a "good wind." By regular exercise, the heart 
and the breathing muscles become strong, and, in con- 
sequence, the blood is circulated better, and a larger 
amount of oxygen is received into the body, thus im- 
parting vigor and life to all the tissues. 

351. How to Exercise. — To be thoroughly useful, 
exercise must be taken regularly, and must bring into 
vigorous action all the muscles of the body, and es- 
pecially those that are least used in the daily business. 
For girls, general housework, sweeping, dusting, making 
beds, and similar household employments, afford excel- 
lent exercise, bringing into play the whole muscular 
system in an admirable manner. The confinement in- 
doors, however, is objectionable. All persons whose em- 
ployment is sedentary, or in-doors, should take out-of- 
door exercise daily. 

For boys, no general exercise excels that which may 
be secured in " doing chores" about the house. Split- 
ting and carrying wood, running errands, and engaging 
in the numberless varied employments included under 
the head of " chores," if heartily entered into, secure 
ample exercise for all parts of the body. When really 
enjoyed, muscular labor of some sort affords a most use- « 
ful form of exercise. It should be added that even 
those w r ho engage in muscular employments may take 
with benefit various exercises for the purpose of bring- 
ing into action muscles which are not much used in the 
daily labor. Such persons require special exercises to 
secure equal and symmetrical development of the body. 

352. Gymnastic Exercises are invaluable as a means 
of general exercise for all classes, and especially for stu- 
dents and young persons. Properly managed, they call 
into action all the muscles of the body in the manner 



200 SECOND BOOK IN PHYSIOLOGY. 

best calculated to secure beneficial results. Many ex- 
cellent exercises may be taken in the school -room at 
intervals during the day with great advantage, even if 
but four or five minutes at a time are devoted to them. 
It is better still to set apart in every school and every 
home a room where exercises may be taken at stated 
hours under proper supervision. The simple apparatus 
needed may be provided at small expense. 

353. Mental Influence of Manual Training. — 
One of the most important results of exercise is its influ- 
ence upon the mind. This sort of culture increases not 
only muscular power, but brain and nerve power as well. 
Every muscular contraction requires the action of the 
brain and nerves to produce it, so that muscular exer- 
cise is also nerve exercise ; and by it the nerves as well 
as the muscles are made more vigorous and efficient. 
The difference between a body well trained and devel- 
oped and one that is not, is enormous. A body w r hose 
every muscle is trained to precision of movement is as 
much more efficient and useful than an untrained body 
as the well-trained horse is more serviceable than the 
clumsy, unbroken colt. Vigorous muscular exercise is 
conducive to good morals, by maintaining a state of 
high health. A young man who feels a just pride in 
his physical strength will avoid evil practices, in order 
to preserve his vigor. 

By prolonged and systematic practice the strength of 
the muscles may be enormously increased. Dr. Win- 
ship, a man of medium size, after many years of practice 
became able to lift with ease the enormous weight of 
two thousand eight hundred pounds. 

354. Symmetrical Development. — It is important 
that the body should be developed symmetrically ; that 



HOW TO KEEP THE MUSCLES HEALTHY. 201 

is, that the two sides should be trained alike. Most per- 
sons are right-handed. In consequence of constant 
training, the right hand and arm become not only larger 
and stronger than the left, but more skilful. Right- 
handed persons always employ the right hand to do 
anything requiring dexterity. If we should give equal 
attention to the left hand, it would become equally 
large, strong, and useful. The ability to use both hands 
equally well would almost double their usefulness. 

Violent exercises of every description should be avoid- 
ed, especially by young persons. Many of the games 
so popular among school-boys and young men are harm- 
ful, on account of the extremely violent exertions likely 
to be made in the excitement of the game. A person 
who has not been accustomed to vigorous exercise should 
begin with very light exercise, always stopping short of 
extreme fatigue, and increasing the amount of muscular 
work from day to day. 

Physiologists have observed the curious fact that if a 
muscle is stimulated when it is weighted with a load 
greater than it can lift, it elongates at the moment of 
action instead of shortening. This very clearly shows 
the danger of attempting to lift weights so heavy as to 
require violent straining, or to engage in any kind of 
exercise requiring excessive muscular efforts. By this 
overstretching, the muscles may be permanently weak- 
ened. 

355. Unrestrained Movement Necessary. — A 
muscle which is hampered by the pressure of tight or bad- 
dly fitting clothing performs its work very imperfectly 
indeed. Yery firm pressure will temporarily paralyze a 
muscle by preventing the expansion which must accom- 
pany contraction (Experiment 20, page 276). The breath- 



202 



SECOND BOOK IN PHYSIOLOGY. 




Fig. 38. — Improper Position. 



ing organs especially should 
have the greatest freedom of 
movement during exercise. 

356. Effects of Improp- 
er Positions. — " As the twig 
is bent, so the tree is inclined," 
is an adage which applies with 
full force to the human body. 
Its yielding structures read- 
ily mould themselves into 
unnatural and unhealthful 
forms when the body is al- 
lowed to assume positions 
which favor such changes. This is especially true dur- 
ing infancy and childhood, when the bony framework 
of the body is still soft and 
yielding. Unhealthful pos- 
tures may be assumed in 
sleeping, sitting, standing, or 
walking. These erroneous 
postures may produce defor- 
mity, and predispose to dis- 
ease. Children should be 
carefully taught to maintain 
proper positions, so that all 
parts of the body may devel- 
op equally and healthfully. 

357. Effects of Alcohol 
upon the Muscles. — We 
have learned that muscular 

fibres are composed of living matter, which acts when 
the muscle works. Observations show that alcohol has 
the effect to paralyze living cells. Its injurious influence 




Fig. 39. — Proper Position. 



HOW TO KEEP THE MUSCLES HEALTHY. 203 

upon muscular fibres is, in part at least, due to the same 
cause. The weak and helpless condition of a man who 
is deeply intoxicated is evidently the result of very pro- 
found poisoning. 

35S. Alcohol and Muscular Degeneration. — 
"When used for a longtime, alcoholic drinks, particularly 
the stronger liquors, cause the muscles to become pale, 
weak, and flabby. Sometimes their natural structure is 
changed to fat. This is one cause of the drao^ino: irait 
and >* chap-fallen " countenance of an old drunkard. The 
heart and the muscular walls of the blood-vessels ap- 
parently undergo this destructive change more rapidly 
than other muscular structures. Intemperate men often 
die from heart failure and apoplexy. The notorious 
prize-fighter Sullivan became a physical wreck through 
alcohol. 

359. Alcohol and Strength. — Scientific investiga- 
tion has shown that the general supposition that alcohol 
gives strength is an error. Alcohol actually lessens mus- 
cular strength. A man who is exhausted with labor takes 
a glass of liquor and feels refreshed, but he has really 
gained no strength. He thinks himself stronger, be- 
cause the alcohol has benumbed the nerves which tell 
him of his true condition. Eeal strength can be increased 
only by rest or by taking food. As we have elsewhere 
learned, alcohol is in no proper sense a food. It is prop- 
erly compared to a whip. A man who is exhausted 
may force himself to further effort by taking alcohol, 
just as a whip would excite a horse under the same cir- 
cumstances ; but the extra effort is a draft on his future 
strength which will be felt sooner or later. 

The late Dr. Parkes, of England, an eminent sanitary 
authority, made many experiments to determine the re- 



201 SECOND BOOK IN PPIYSIOLOGY. 

lation of alcohol to working ability, having in his mind 
the " grog ration " of the British army, of which he was 
the chief sanitary officer. His conclusion was most de- 
cided that alcoholic drinks in any appreciable amount 
materially lessen a man's ability to endure severe mus- 
cular exercise. He observed that a laboring-man, after 
taking whiskey, felt as though he could do more work 
than without it, but when he undertook the task he was 
unable to do as much. General Lord Wolseley, com- 
mander-in-chief of the English army, cut off the " grog 
ration " during the war in Egypt, prohibiting the use of 
liquor among the soldiers, and with such good results 
that he adopted the same practice during the subse- 
quent war in the Soudan, and allowed no liquor to be 
sold within many miles of his camp. He testifies that 
this course resulted in saving an immense amount of 
sickness among the troops. 

Recently (1893) the writer undertook a series of ex- 
periments for the purpose of determining the influence 
of alcohol upon muscular strength. The subject chosen 
for the experiment was a young man about twenty 
years of age, who had never been addicted to the use 
of alcoholic drinks in any form. This young man's 
strength was tested by means of an instrument which is 
capable of recording successively the strength of each 
group of muscles in the body. The sum of all the tests 
represents the entire strength of the body. In this case 
the total strength of the yoang man upon whom the ex- 
periment was made was found to be equivalent to a lift- 
ing power of 4881 pounds. This amount represents the 
successive lifts made by the different groups of muscles 
in the young man's body. After giving two ounces of 
whiskey, the strength of each group of muscles was again 



now TO KEEP THE MUSCLES HEALTHY. 205 

tested, when it was found that the young man's total 
strength was 3385 pounds, nearly 1500 pounds less. 
The total strength was thus diminished nearly one-third. 
Under the influence of alcohol, a man often thinks his 
strength to be increased, but scientific observations show 
it to be less. 

360. Tobacco and Development. — It has long been 
known that tobacco dwarfs the body and hinders the 
development of the mind. In France and some other 
European countries the use of tobacco is on this account 
forbidden to all students in the public schools. More 
recently our own Government has taken a step in the 
same direction, in forbidding the use of tobacco by the 
students of its military and naval schools. All medical 
authorities agree that tobacco is wholly bad for boys 
and young men. Is it not evident that a drug so pow- 
erful as to interfere seriously with the growth of the 
body must likewise seriously interfere with its proper 
repair and its various nutritive processes, even if used 
when the body has attained its growth ? The harm may 
be less apparent in adults, but that mischief is done can- 
not be doubted. 

361. Tea and Coffee. — Tea and coffee, like alcohol, 
relieve the sensation of weariness and exhaustion in 
a most remarkable manner, but do not really increase 
the strength. On this point Dr. Edward Smith, F.E.S., 
who made a very exhaustive study of the effects of tea 
and coffee many years ago, remarks : " They should not 
be taken by the young or the very feeble. Their essen- 
tial action is to waste the system or consume food, by pro- 
moting vital action which they do not support" And in 
a recent work he says that these statements " have not 
been disproved by any scientific researches." 



206 SECOND BOOK IN PHYSIOLOGY. 

The effect of coffee and similar beverages is identi- 
cal with that of tea. Coca, a South American plant, the 
leaves of which are used in the same manner as tea, has 
been credited with remarkable power to sustain mus- 
cular effort ; but that the apparent strength afforded is 
only apparent, and really of the nature of excitement, 
as in the case of tea, is evident from the following de- 
scription of the effects of the continued use of this drug, 
given by Dr. C. Hartley, an eminent South American 
traveller : " He [the coca-eater] is known at once by his 
uncertain step, his sallow complexion, his hollow, lustre- 
less, black-rimmed eyes, deeply sunk into his head, his 
trembling lips, incoherent speech, and his stolid apathy." 

In regard to the effect of tea upon the muscles, Dr. 
Smith remarks that, under the influence of tea, " there 
is a greater readiness for, and ease in making, muscu- 
lar exertion ; but if it is indulged, a greater sense of ex- 
haustion follows." 

It thus appears that tea and coffee, as well as alcohol, 
are deceivers, and most physicians now recognize the 
fact that they are capable of great mischief when freely 
used. Hot milk is more refreshing than tea or coffee, 
and is nourishing as well. 

SUMMARY. 

1. Regular and systematic exercise is necessary to maintain the mus- 
cles in health. 

2. Muscular exercise quickens the activity of all the vital organs. 

3. Training of the muscles also develops the brain and the nerves. 

4. Both sides of the body should be developed equally. 

5. Alcohol and tobacco cause paralysis and degeneration of the 
muscles, lessen muscular strength, and hinder pli3 r sical development. 

6. Tea and coffee increase the exhaustion from labor. 



CHAPTER XXVII. 
THE BRAIN AXD THE NERVES. 

362. The Governing Organs of the Body. — In 

a complicated structure like the human body, in which 
each part is dependent on many others, a special ar- 
rangement is needed to secure perfect harmony of 
action. For example, when a child, not knowing the 
properties of fire, puts its finger against a hot iron, the 
muscles of the arm by quickly drawing the hand away 
save it from serious injury. When we are exposed to 
excessive heat, the skin pours out the perspiration to 
cool us off. When we run, the lungs and heart work 
faster to supply oxygen to support the muscles in their 
increased activity. Thus the numerous workers in the 
body mutually assist and protect each other, and, w T hen 
in health, work in most perfect harmony. This har- 
mony of action is the result of the activity of a set of 
organs whose functions render them the most remark- 
able of all vital structures. These organs constitute the 
nervous system. 

363. Nerve Tissue. — There are two forms of nerve 
tissue, viz., nerve cells and nerve fibres. Really, the nerve 
fibres are merely appendages to, or prolongations of, 
the cells. Most nerve cells send out two or three slen- 
der arms, one or more of which may be prolonged into 
nerve fibres, while the others connect with similar arms 
of other cells, or, after running out a short distance 



208 



SECOND BOOK IN PHYSIOLOGY. 



from the cells, terminate in the 
spaces between them. Every nerve 
fibre is composed of minute threads 
of living matter, each of which 
comes from a nerve cell. The nerve 
fibres extend into all parts of the 
body. 

364. Nerve Centres. — The nerve 
cells are usually found in groups. 
A group of nerve cells which has 
charge of some particular part of 
the body, or of some special work, 
is called a ganglion or nerve centre. 
Thus we have centres which regulate 
the action of the heart, sweat centres, centres to control 
the muscles, etc. The brain is made up of nerve centres. 




Fig. 40. — Nerve Cells. 




Fig. 41. — A Ganglion. 
a, b, c, c, Nerve Fibres, d, Nerve Cells, 



365. Nerve Trunks. — The little bundles of nerve 
fibres which pass out from the nerve centres unite to 



THE BRAIN AND THE XKUVES. 



209 



form larger bundles, which pass off into the different 
parts of the body, giving off iibres to the various parts 
for which they are designed. These bundles of nerve 
fibres are termed nerves or nerve trunks. In dissecting 
the body of an animal, they are found as white glisten- 
ing cords running everywhere among the tissues. 

366. The Brain. — Within the skull is to be found 
by far the largest and most important mass of nerve 
tissues in the body. The entire contents of the skull 
constitute the brain. 

The average weight of 
the brain is about fif- 
ty ounces in men, and 
a few ounces less in 
women. With the ex- 
ception of the whale 
and the elephant, the 
human brain is larger 
than that of any oth- 
er animal. 

The following are 
the weights of a few 
of the heaviest brains which have been weighed : Cuvier, 
sixty-four and a half ounces; Abercrombie, sixty-three 
ounces ; Daniel Webster, fifty-three and a half ounces ; 
a London bricklayer, sixty- seven ounces. An idiot's 
brain is smaller than an ordinary brain, sometimes weigh- 
ing less than one-third as much. 

367. Coverings of the Brain. — The brain is ex- 
ceedingly delicate in structure, and, besides the protec- 
tion afforded by the skull, it is covered by membranes, 
between which is found a small quantity of fluid which 
still further protects the brain from possible injury. 




Fig. 42.— The Brain— Side View. 



210 SECOND BOOK IN PHYSIOLOGY. 

368. The Cerebrum. — The large mass of nerve tissue 
which fills the upper part of the skull is known as the 
cerebrum. In man this part of the brain is larger, in 
comparison with the remaining portion, than in any 
other animal. A deep fold of its covering membranes 
divides the cerebrum into two halves, right and left, 
termed hemispheres. The surface of the brain presents 
irregular ridges and furrows, forming the convolutions, 

369. The Cerebellum. — Beneath the back part of 
the cerebrum is found the next largest mass of nerve 
matter in the skull, the cerebellum, or little brain. The 
form of the cerebellum is similar to that of the cerebrum. 
Like it, also, it is divided into a right and a left half. 

370. White and Gray Matter. — The outside of 
both the cerebrum and the cerebellum is covered with 
layers of nerve cells to the depth of about one-sixteenth 
of an inch. From its color, this is known as grav mat- 
ter. Underneath the gray matter the brain tissue pre- 
sents a glistening white appearance. This portion is 
composed of fibres. 

The total number of cells in the brain has been esti- 
mated to be about 1,200,000,000. 

The brain is not sensitive to pain, and may sustain a 
severe injury without destroying its usefulness. A man 
had a large blasting-iron driven through his skull and 
through one hemisphere of his brain. The bar enter- 
ed the skull below the ear, coming out at the top of 
the head. He recovered from the accident, and enjoyed 
fair health for many years, although a considerable por- 
tion of one-half of the brain had been destroj^ed by the 
accident. His intellect was not materially impaired, but 
his disposition seemed somewhat changed. 

371. The Central Ganglia. — At the under side of 



THE BTCAIN AND THE NERVES. 



211 



the cerebrum are a number of collections of nerve cells 
known as the central ganglia. The most important of 
these are the optic thalamus and the corpus striatum. 

372. The Medulla Oblongata.— The extreme lower 
part of the brain, a rounded portion lying just above 
the large opening in the 

base of the skull, is called 
the medulla oblongata. The 
medulla differs from other 
parts of the brain in hav- 
ing its gray matter, or cells, 
in its centre, the white mat- 
ter being arranged upon 
the outside. 

The several divisions of 
the brain are joined to- 
gether by a portion called 
the pons. 

373. The Spinal Cord. 
— The nerve substance pro- 
longed downward from the 
brain through the spinal ca- 
nal is called the spinal cord. 
Its length is from fifteen 
to seventeen inches, and its 
diameter is one -half an 
inch. Like the medulla ob- 
longata, the central portion 

of the cord is composed of gray matter, the outer of 
w T hite. It is protected by membranes like those w r hich 
cover the brain. The cord is divided into a right and 
a left half, each of which is again divided into several 
bundles, termed columns. 




Fig. 43. — Brain and Spinal Cord. 



212 



SECOND BOOK IN PHYSIOLOGY. 



374. Nerves of the Brain and the Spinal* Cord. — 

The various parts of the brain and the spinal cord send 
out nerve trunks, numbering forty-three pairs in all. 
Twelve of these arise from the under side of the brain, 
and are termed cranial nerves ; the remaining thirty -one 
are given off by the spinal cord, and are called spinal 

nerves. The cranial nerves 
leave the brain through 
small openings in the base 
of the skull. They are dis- 
tributed to the face, to the 
organs of sense — eye, ear, 
nose, and mouth — and to 
the organs of the chest and 
the abdomen. The spinal 
nerves pass out from the 
spinal cord through open- 
ings in the sides of the 
spinal canal. Each nerve 
arises from the cord by two 
roots — one from the back 
part of the cord, the other 
from the front part. The 
spinal nerves are distributed to the trunk and the ex- 
tremities. The brain, the spinal cord, and the nerve 
trunks which they give off, together constitute what is 
termed the cerebrospinal nervous system. 

The nerves which come from the right side of the 
body cross over to the opposite side in the spinal cord 
and at the base of the brain, so that in cases of paraly- 
sis on one ^sicle of the body the injury to the brain is 
generally found upon the opposite side. 

375. The Sympathetic Nervous System. — With- 




Fig. 44. — Facial Nerve. 



THE BRAIN AND THE NERVES. 213 

in the cavity of the body, and just in front of the spine, 
is placed a row of small ganglia arranged in pairs. 
The ganglia of each pair are connected together, and 
are also connected with the ganglia above and below 
them. Nerve branches are also sent from the different 
ganglia to join the cerebro-spinal nerves, and branches 
are received from them. A few similar ganglia are 
found in the cranial cavity, making in all about thirty 
pairs. These ganglia, and the nerves arising from them, 
constitute the sympathetic nervous system. The sympa- 
thetic nerves are chiefly distributed to the mucous mem- 
brane and to the organs concerned in nutrition — the 
stomach and intestines, the liver, the blood-vessels, etc. 
They derive their name from the fact that by their con- 
nection with the different parts of the body a close sym- 
pathy is established between its various organs. 

SUMMARY. 

1. The brain and the nerves control and harmonize the work of the 
body. 

2. Two kinds of nerve tissue — cells and fibres. 

3. A group of nerve cells having special work is a nerve centre, or 
ganglion. 

4. The nerves are bundles of nerve fibres. 

5. The brain is a collection of nerve centres — weight about three 
pounds. 

6. The brain comprises the cerebrum, cerebellum, central ganglia, 
medulla oblongata. 

7. The brain consists of gray matter — cells ; and white matter— fibres. 

8. The spinal cord is also made up of gray and of white matter. 

9. The cerebro-spinal system comprises the brain, spinal cord, 
twelve pairs of cranial nerves, and thirty-one pairs of spinal nerves. 

10. There are thirty pairs of sympathetic nerve centres. The sympa- 
thetic nerves are chiefly distributed to the mucous membrane and to 
the organs of nutrition — heart, stomach, liver, blood-vessels, etc. 



CHAPTER XXVIII. 
HOW WE FEEL AND THINK. 

376. Sensory and Motor Nerves. — It has been 
shown by experiment upon animals that if a nerve going 
to any part is cut, the application of electricity to the 
outer portion of the nerve causes the muscle to contract, 
but produces no pain ; while if electricity is applied to 
the inner portion, pain is felt, but no muscular contraction 
occurs. This experiment demonstrates that nerve trunks 
are made up of two kinds of fibres, one carrying impres- 
sions inward, to the brain or spinal cord, and the other 
carrying impulses outward, to the muscles or other or- 
gans. Those nerve fibres which convey impressions in- 
ward are termed sensory fibres ; those which transmit 
impulses outward are called motor fibres. The sensory 
and the motor fibres are generally bound together in 
the same nerve bundles. This is true of the spinal 
nerves, at least. Most of the cranial nerves are com- 
posed of either sensory or motor fibres exclusively. 

377. Different Kinds of Sensory Nerves. — The 
nerves of sense or feeling are not all alike, for we experi- 
ence many different kinds of sensations. Hearing, see- 
ing, smelling, tasting, and feeling are all special kinds 
of sensation. We are also able to distinguish heat and 
cold, and to determine the weight of objects. Besides 
these special sensations, we have a number of general 
sensations, such as pain, fatigue, hunger, thirst, nausea, 



HOW WE FEEL AND THINK. 215 

the desire for air, etc. For each of these different kinds 
of sensation there is in the brain a special group of cells 
which has charge of that particular sense. From each 
special group of cells nerves go out to the various parts 
of the body, or to some particular part of it, as the eye, 
the ear, or the nose ; and it is through these nerves that 
the various impressions which give rise to sensations are 
received. We shall learn more of the nerves of special 
sense in a future chapter. 

378. Different Kinds of Motor Nerves. — The 
nerves of work, or motor nerves, also differ greatly in the 
kind of work which they control. This is due to the fact 
that they are connected with different groups of cells in 
the brain, each of which has charge of some particular or- 
gan or class of organs. Thus, one group of cells and its 
nerves control the muscles ; another, the heart ; another, 
the stomach. So, also, the liver, the lungs, the kidneys, 
and all other important organs in the body have each 
their controlling centres and nerves. Such acts as cough- 
ing, sneezing, vomiting, etc., are under control of certain 
groups of cells in the brain, by which they are induced. 
A very important set of nerves of this class are known 
as vaso-motor nerves. These nerves are distributed to the 
heart and the blood-vessels. They control the circulation, 
by regulating the size of the small blood-vessels, causing 
their muscular walls to contract or dilate as the tissues 
may need less blood or more. Blanching and blushing 
of the skin are due to the action of these nerves and their 
nerve centres. 

379. Essential Nature of the Brain. — Essentially 
a brain is simply a collection of nerve cells, which re- 
ceive impressions through one set of nerve fibres, and 
send out impulses through another. Some lower animals 



216 SECOND BOOK IN PHYSIOLOGY. 

have no brain, or we might say, perhaps, have many 
brains, since they have numerous groups of nerve cells 
placed in various parts of the body. When Ave touch the 
finger to a hot surface, the sensory nerve fibres in the fin- 
ger transmit a painful impression to certain cells in the 
brain, which are set apart to receive such impressions. 
These, in turn, send an impulse to other cells, from which 
nerve fibres are distributed to the muscles controlling 
the arm. These cells send out an impulse to the proper 
muscles, which are thus made to contract, and the hand 
is drawn away. Thus we have special cells to receive 
impressions, or sensory cells, which give rise to sensory 
fibres, and special cells to send out impulses, or motor 
cells, from which arise motor fibres. 

380. How Nerves Conduct. — The exact manner 
in which nerves conduct impressions is not eas}^ to com- 
prehend. The process may be roughly compared to the 
action which passes along a row of bricks set on end, 
and such a distance apart that when a brick at one end 
of the line is made to fall over it will strike the next, 
which in turn will fall against the next, and so on until 
all have fallen. The impulse given to the first brick 
will be transmitted through the intervening bricks to the 
last, no matter how great the length of the line. If we 
imagine the line of bricks to be a nerve fibre, one end 
terminating in the skin, while the other is connected to 
a cell in the brain, we may form a rude conception of 
how an impression may be conducted along the living 
particles composing a nerve. We can also imagine how 
a cell may, on receiving an impression through a nerve 
fibre, start it off to another cell over another nerve 
filament. Nerve force travels only on nerve fibres. 

381. Nerve Force or Energy. — A slight nervous 



HOW WE FEEL AND THINK. 217 

impression, as a sudden noise, or even simply tickling the 
skin, may cause very vigorous muscular action. To ex- 
plain this, let us return to our illustration. We may sup- 
pose that the last brick, when it falls, releases a spring 
which has been set as a boy sets a steel-trap for a rat, and 
which in action manifests much more force than was re- 
quired to spring it. It requires but a small touch to 
release the spring, although when it acts it exerts a 
great amount of force. The cells of the brain and the 
spinal cord, as well as the muscles, are constantly storing 
up energy, to be released as thought or action when the 
proper stimulus comes. 

3S2. How long it takes to Feel. — When the hand 
comes in contact with a hot surface, we seem to feel the 
heat instantaneously; but careful experiments, which 
have been made upon animals and upon human beings, 
show that a little time elapses between the instant of con- 
tact and the recognition of the sensation. In other words, 
a certain time is required for the sensation to travel over 
the sensory nerve to the centre of the brain or the spinal 
cord. A certain additional time is also needed for the 
impulse to travel from the nerve centre to the muscles, 
to cause them to contract. Experiments show that the 
nerve force travels at the rate of about one hundred feet 
a second. Thus a whale one hundred feet long would 
not feel a harpoon thrust into his tail until a second had 
passed ; and another second would elapse before he could 
begin to move the injured member. 

383. Reflex Action. — When sensation gives rise to 
motion, as when the finger is withdrawn from a candle- 
flame, the action is said to be reflex, because the impres- 
sion made at the ends of the nerves of the skin is car- 
ried to the nerve centre having charge of the part, and 



218 SECOND BOOK IN PHYSIOLOGY. 

reflected back as an impulse which causes the muscles to 
contract and withdraw the hand. This action requires 
no conscious effort of the will. A great share of the 
movements of the body are reflex acts. When we look 
on an object and then put out the hand to take it, the 
action is really a reflex of an impression received through 
the eye ; and so with each of the senses. Many reflex 
acts are performed without voluntary effort, as breath- 
ing, winking, swallowing, talking, and vomiting. This 
is indeed a great blessing to us. By means of this ad- 
mirable arrangement the mind is relieved of a great 
amount of routine work. 

Somnambulism, or sleep-walking, is a reflex act of a 
very high order. Sleep-walkers will frequently per- 
form, when asleep, feats which they would find impossi- 
ble, and would not even dare to undertake when awake. 
A sleep-walker should never be awakened when in a 
dangerous position. 

By long practice many actions which are at first vol- 
untary, requiring constant exercise of the will, may be- 
come reflex, as the act of walking. When a child first 
attempts to walk, a voluntary effort is required each 
time the foot is raised and put forward. After a time, 
however, the action becomes reflex, so that he can walk 
a long distance while the mind is wholly absorbed in 
thought, and without giving any voluntary attention to 
the feet and legs. The movements of the hands and fin- 
gers, in playing on the piano and other musical instru- 
ments, as well as the bodily movements employed in 
many trades, are very largely reflex. It would other- 
wise be impossible to attain a great degree of skill in 
any art or trade. 

384. Automatic Action. — Keflex actions originate in 



HOW WE FEEL AND THINK 210 

the impressions brought to the nerve centre by sensory 
nerves. Some centres are capable, under certain circum- 
stances, of originating and sending out impulses without 
being excited by an impression received through the 
sensory nerves. These are termed automatic centres, 
and the actions which they induce are said to be auto- 
matic. For example, the heart of a turtle or a frog, 
when removed from the body, will continue to beat for 
hours, through impulses received from nerve cells in the 
heart itself. The action of the lungs, liver, stomach, 
and many other vital organs, is automatic. 

385. Uses of the Spinal Cord. — It sometimes hap- 
pens that a severe injury to the spine at some point 
causes paralysis of the parts below the seat of injury. 
No effort of the will can cause the muscles of the limbs 
to move, and no application which can be made w T ill 
produce pain or sensation of any sort. A hot iron ap- 
plied to the foot produces no pain, even though the 
flesh may be severely burned ; but if we tickle the bot- 
tom of the foot, it will be jerked away by a strong 
contraction of the muscles, although the person will 
feel nothing, and may not even know that his foot has 
moved unless he is looking at it. The feet of a person 
who is sound asleep will move in the same manner 
when tickled. This fact shows clearly that there are 
in the spinal cord cells which, without the action of the 
brain, possess the pow T er to send out impulses to the 
muscles in response to impressions received through the 
sensory nerves. Man} 7 reflex actions of like character, 
which are performed by the spinal cord alone, are con- 
stantly taking place. Indeed, the execution of reflex 
actions may be regarded as the chief function of the 
spinal cord. It also gives passage to numerous nerve 



220 SECOND BOOK IN PHYSIOLOGY. 

fibres which go upward to the brain from the various 
parts of the body, and to others which pass out from the 
brain to be distributed to the various organs and tissues. 

386. Uses of the Medulla Oblongata, — This organ, 
which is an expansion of the upper end of the spinal 
cord, is, like the spinal cord, a centre for reflex and auto- 
matic actions, especially those which are of the greatest 
importance to the body, as respiration, heart action, and 
the regulation of the blood-vessels. It also contains nerve 
centres for dilating the pupil and for closing the eye, 
for vomiting, swallowing, mastication, and suction. The 
importance of this part of the nervous system is shown 
by the fact that the mere puncture of the brain with a 
needle at this point is sufficient to cause death. From 
this fact, the medulla has been termed the " vital knot." 

387. Uses of the Cerebellum. — It has been found 
that removal of the cerebellum of birds and other ani- 
mals deprives them of the power to make regular move- 
ments. Diseases of this organ in human beings pro- 
duce similar results, from which it is concluded that its 
chief office is to regulate or co-ordinate the movements 
of the muscles so as to cause them to act in harmony 
and with precision. An intoxicated person cannot walk 
steadily on account of the paralyzing effect of alcohol 
upon the cerebellum. 

388. Uses of the Cerebrum. —The experiment of 
removing the hemispheres from the brain of a frog, or 
other animal, has been made by physiologists for the 
purpose of studying the condition of an animal when 
deprived of these large masses of nerve tissue. The 
animal does not die at once, as might be expected ; but, 
if it be a frog or a pigeon, may be kept alive for some 
time. It is observed, however, that a most important 



HOW WE FEEL AND THINK. 221 

change has taken place in an animal which has been 
treated thus. If it be a frog-, it will swim when placed 
in water, will hop when pinched or otherwise stimu- 
lated, will creep up the side of a board on which it has 
been placed, when it is tilted, and will croak when its 
sides are stroked. Thus it appears very much like any 
other frog, but it seems to have no sense. If made to 
hop by pinching its back, it will hop into the fire as 
readily as elsewhere. If left alone, it will remain with- 
out stirring until it perishes. It has no power to origi- 
nate impulses. It has no intelligence. 

It has been observed that disease of this part of the 
brain in human beings impairs the intelligence, and that 
the larger the cerebrum in proportion to the rest of the 
brain, and to the whole animal, the greater the intelli- 
gence of the animal. From these facts, it is evident that 
the cerebrum is the organ of the mind or the intelligence. 

It has recently been discovered that every part of the 
muscular system is represented in the gray matter cov- 
ering the cerebrum. Each group of muscles has a cor- 
responding group of cells in this portion of the brain, by 
which it is controlled. 

389. The Central Ganglia.— These groups of nerve 
matter, located at the base of the brain, are chiefly de- 
voted to certain reflex actions connected with sensation, 
which are at first performed by the cerebrum, but are 
by degrees passed over to these centres, so as to relieve 
the cerebrum, and permit it to do other and higher 
kinds of work. Walking, writing, piano -playing, and 
other acts which become reflex by long practice, are 
largely performed by the central ganglia. In sleep- 
walking these centres are active, although the higher 
centres may be wholly inactive. The central ganglia 



222 SECOND BOOK IN PHYSIOLOGY. 

may be very properly called the servants of the cere- 
brum, since they are always in waiting to carry out its 
orders, and after long education become so trained that 
they can clo some kinds of work without the supervision 
of the higher centres, by this means relieving them of 
much labor and drudgery. The acquirement of an art or 
a trade consists chiefly in the training of these centres, 
without which manual " skill" would be impossible. 

390. Relation of Mind and Body. — Whatever may 
be the real nature of the mind, the close relation of the 
body and the mind is too evident to be doubted. Dis- 
eases of the body affect the mind, and disorder of the 
mind affects the body. Even the involuntary actions 
of the body, as the beating of the heart, digestion, etc., 
are affected by the mind. 

391. Inhibition. — Among the most interesting groups 
of nerve cells found in the brain are certain ones which 
are charged with the duty of restraining other nerve 
centres. For example, there is a centre which causes 
contraction of the small blood-vessels, the vaso- motor 
centre. If allowed to act freely, the blood-vessels would 
be strongly contracted all the time. Another centre 
exercises a restraining influence upon the vaso -motor 
centre, so that it is. allowed to stimulate the vessels to 
contract only so much as is necessary to regulate the 
blood supply of the various parts of the body. The 
controlling centre exerts upon the acting centre the 
same influence as a "governor" upon a steam-engine. 
This action is called inhibition. The disposition to sneeze 
may be counteracted by pressing hard upon the upper 
lip, or rubbing upon the upper part of the nose with the 
thumb and finger. Coughing may be usually controlled 
by an effort of will. These are examples of inhibition. 



HOW WE FEEL AND THINK. 223 

There are many inhibitory centres in the brain. The 

most important of all are those by means of which 
we exercise self-control. Judgment, reason, fear, con- 
science, hope— all inhibit other parts of the brain which 
might lead us to actions which we would regret. When 
we are young Ave express our emotions without re- 
straint, in laughing, crying, etc. When we become old- 
er we learn to control our feelings. Some persons do 
not learn this as they should, and make much trouble 
for themselves and others by their lack of self-control, 
giving way to fits of anger or grief in a most reckless 
manner. One of the most important uses of the front 
part of the large brain is to inhibit the action of other 
parts of the nervous system. 

392. Habit. — When once an act has been performed, it 
is easier to perform the same act the second time ; and 
each time the act is repeated it is done with a little 
greater ease, until after a time it is done without thought 
and without any effort of the mind, because the central 
ganglia have been educated to do it. The act has now 
become habitual, and we say it is a habit. 

We form habits in relation to mental and moral acts, 
as well as in respect to merely mechanical acts, as walk- 
ing, eating, etc., and in precisely the same way. When- 
ever we do a wrong act, it becomes easier to do the same 
again, and our power of resisting temptation is lessened 
with each repetition of the act. On the other hand, our 
resolution and ability to resist evil are strengthened 
each time we overcome a temptation to do wrong. 
Hence the importance of cultivating right habits. Con- 
sider, when tempted to do a wrong act, that it will leave 
behind it an effect upon the brain which may not be 
easily effaced. We should cultivate good thoughts, good 



224 SECOND BOOK IN PHYSIOLOGY. 

habits, good manners, until they become second nature, 
or habitual. 

393. Memory. — The faculty of recalling past mental 
impressions is memory. Memory is a property of nerve 
cells. Some objects give off light in the dark after 
having been exposed to the sunlight. This property is 
termed phosphorescence. In the same way nerve cells 
may give off or revive the impressions which they have 
received. Memory is a sort of organic phosphorescence. 
The thing most essential for a good meraor}^ is that the 
first impression shall be strong. For this it is necessary 
that the attention should be concentrated upon the thing 
to be memorized, and the mind kept free from all other 
ideas until it is fully comprehended and thoroughly im- 
pressed upon the mind. Memory may be greatly im- 
proved by cultivation. It forms the basis of habit. 

SUMMARY. 

1. Two kinds of nerves — sensory and motor. 

2. Sensory nerves — general sensation," as pain, hunger, fatigue, thirst, 
etc., and special sensation, as hearing, sight, taste, smell, touch. 

3. Motor nerves control the muscles, lungs, liver, stomach, coughing, 
sneezing, vomiting, etc. 

4. A brain receives impressions and sends out impulses. 

5. Nerve force is stored in nerve cells; it travels at the rate of about 
one hundred feet per second. To feel requires perceptible time. 

6. Most acts, even voluntary acts, are reflex. 

7. The automatic centres act independently of sensation or volition. 

8. The spinal cord both transmits and originates impulses, and gives 
rise to reflex acts. 

9. The medulla oblongata is a reflex and an automatic centre — con- 
trols heart, regulates blood-vessels, respiration, vomiting, swallowing, 
etc. 

10. The repetition of an act renders its performance easier; when it 
becomes automatic it is a fixed habit. 

11. Memory is a property of nerve cells. It may be improved by 
cultivation. 



CHAPTER XXIX. 
HYGIENE OF THE BRAIN AND THE NERVES. 

394. Mental Exercise Necessary. — Exercise is 
quite as essential to the health of the brain and the 
nerves as to that of the muscles. A brain which is not 
used rapidly loses its ability to do mental work. Men- 
tal exercise develops mental strength and capacity, just 
as muscular exercise develops muscular strength and skill. 
That brain work is healthful is shown by the fact that 
great thinkers, scholars, philosophers, and other brain 
workers are the longest lived of all classes of men. 

Brain exercise, to be healthful, must be properly regu- 
lated. Too much study is harmful, and weakens rather 
than strengthens the brain. Each brain has only a cer- 
tain number of brain cells, and is capable of holding 
only a certain amount of knowledge. An eminent phys- 
iologist estimates that the most retentive memory can- 
not acquire more than two hundred thousand distinct 
facts, and a much smaller number is probably the limit 
of ordinary minds. When the full capacity of a brain 
is reached, new facts are received only by crowding 
others out. Hence, we should exercise care in selecting 
what we undertake to store up in the mind, so that it 
may not be like a neglected garret, full of all sorts of 
rubbish, without order, and of little practical value. 
Never try to learn or remember what is not worth 
learning or remembering, as it will interfere with the 
retention in the memory of something of real value. 



226 SECOND BOOK IN PHYSIOLOGY. 

395. How to Study. — Proper study makes the mind 
stronger, and able to do a larger amount of mental 
work, just as proper exercise strengthens the muscles. 
There is a right way and a wrong way of studying. 
" Cramming," that is, hastily crowding facts into the 
brain simply by an effort of the memory, is exceeding- 
ly detrimental to the health of the mind. Careless and 
indifferent study is of no value, and injures the mind. 
Students should always endeavor to discover the princi- 
ples involved in what the}^ study, so that they may not 
be obliged to depend upon the mere memory of facts. 
Those who learn by mere repetition, as do parrots, never 
become learned and do not acquire real culture. 

It is not well to study when the brain is weary. The 
impressions then made upon the brain are very slight, 
and soon become indistinct, so that what is learned is 
quickly forgotten. Two or three hours are as much time 
as most students should spend at hard study without at 
least a short rest. A half -hour's exercise in the open air 
will renew, to a remarkable degree, the retentive power 
of the brain and the capacity for study, when the mind 
is weary with continuous work. In school study, the 
most important thing to be gained is mental culture 
and discipline — the ability to use the mind in the 
practical affairs of e very-day life, and in acquiring use- 
ful knowledge. 

396. How to Remember. — A few hints upon the art 
of not forgetting may be of great use to students : 1. Give 
attention. Concentrate the mind intensely upon the 
subject to be learned. " Mind-wandering " is the great- 
est of all obstacles to effective study. Many persons can 
remember almost nothing on account of this infirmity. 
Compel the mind to attend closely to the one thing in 



HYGIENE OF THE BRAIN AND THE NERVES. 227 

hand. 2. Study carefully the relations and associations, 
all the parts and properties, of the thing to be memor- 
ized. 3. Link the new fact to something already so 
familiar to the mind that it cannot be easily forgotten. 
If it is a new word, associate it with a familiar word 
of similar sound or meaning, or even one of opposite 
meaning. The mere act of making such an association 
serves to impress the word upon the mind. 4. If it is a 
list of words to be committed to memory, do not en- 
deavor to force them upon the mind by mere repetition, 
but weave them into a chain of words so arranged that 
each word suggests the one to follow. 

In making such a list one commits it to memory by 
noticing the relations of similarity or contrast between 
each word and the word following it. By this method 
a thousand words can be carried in the memory as easily 
as ten. The memory is strengthened by this method of 
memorizing, while it is often weakened by the ordinary 
method of learning by rote. 

397. Mental Worry. — Worry is in the highest degree 
detrimental to the health of the brain and nerves. A 
brain which will endure without injury a vast amount 
of healthful work will rapidly fail under the influence of 
constant worriment and perplexity. The anxiety and 
wearing mental excitement of the gambler or the stock- 
broker doom him to an early decline of his mental facul- 
ties, or to a premature grave. Brain worry destroys 
many ; brain ivork injures very few. 

398. Evils of Excitement. — Violent mental excite- 
ment exhausts the brain and the nervous system much 
more than ordinary mental or nervous action. Such 
emotions as fear, hatred, jealousy, envy, anger, and all 
of the passions, as well as excessive mirth and joy, are 



228 SECOND BOOK IN PHYSIOLOGY. 

extremely exhausting to the nervous system, and some 
are dangerous to life. Exciting amusements, and the 
reading of exciting books, especially those of a senti- 
mental character, are unfavorable to healthy mental 
growth. Too much reading of any sort is injurious. 
One book worth reading, carefully read and mastered, 
is worth a hundred carelessly and hastily run through. 
Hasty and promiscuous reading weakens the mind and 
destroys the taste for solid and wholesome books. 

399. Sleep. — The brain, like the muscles, when used 
continuously for some hours, or when violently exercised 
even for a short time, becomes clogged with worn-out 
particles from the waste of its tissues, and its nervous 
energy becomes exhausted. When the waste has con- 
tinued as long as is safe or proper, nature warns us of 
the fact by a sensation of mental weariness or drowsi- 
ness. During sleep the waste matters are removed, and 
a new store of nervous energy is accumulated by the 
cells of the brain and other nerve centres. Loss of sleep 
produces irritability of temper and loss of mental vigor. 
The body requires at least seven or eight hours of sleep 
daily. Children and young persons require more sleep 
than older persons. 

400. Nerve Tone. —When the nerve cells contain a 
good store of nervous energy they are said to be in good 
tone. Anything which impairs the bodily health lowers 
the tone of the nerves. Lowered nerve tone involves 
impairment of the mental tone, and produces a corre- 
sponding effect upon the moral tone. 

401. Self-Control. — This is a faculty which is pos- 
sessed in different degrees by different persons. It should 
be cultivated by all as one of the most essential of require- 
ments. It grows, like the other faculties, with use, and 



HYGIENE OF THE HKA1N AND THE NERVES. 229 

weakens with disuse. The usefulness of thousands of 
persons is hopelessly wrecked by lack of self control. 
By the development and exercise of this faculty the 
mind may be kept free from evil thoughts. The Jiasty, 
profane, or unclean word will be checked before it is 
spoken, and the appetites and passions which lead so 
many to ruin will be held in subjection. 

A brain may be compared to a picture-gallery, in 
which hang the portraits of a long line of ancestors 
reaching back to Adam. Time may have effaced their 
features, but the outlines are distinct, some shapely and 
beautiful, others deformed and hideous. It is well for 
us to remember that our own portraits, sketched true to 
life by an artist more exact than the most skilful paint- 
er, may hang in the mind-galleries of the generations to 
come. 

402. Food and Brains.— The brain, like the rest of 
the body, is made of what we eat. An old German 
proverb runs, " As a man eateth, so is he." This is es- 
pecially true of the brain. If the blood is filled with 
pungent spices and irritating condiments, it will excite 
the nerves, causing irritability and nervousness. Exces- 
sive use of animal food causes similar results, producing 
undue nervous excitability, especially of the lower fac- 
ulties of the mind. The food must contain an abun- 
dance of those elements which build up the nervous sys- 
tem, particularly the phosphates and the albuminous 
elements. Such whole-grain preparations as Graham or 
entire wheat flour, also peas, beans, eggs, and milk, con- 
tain phosphates in good proportion. 

Students should by no means conceive the idea that 
they need little food. The brain needs for its support 
an abundance of the best food ; but eating too much 



230 SECOND BOOK IN PHYSIOLOGY. 

must be carefully avoided, since excess clogs the brain as 
well as the other tissues. Overeating is a common cause 
of mental dulness. Students, above all others, need to 
attend closely to the rules of diet. Much of the head- 
ache, dulness, and mental confusion which are attributed 
to overstudy or mental incapacity are really due to im- 
perfect digestion, which furnishes the brain with poor 
material, and poisons it with the products of indigestion. 
403. Necessity for Muscular Exercise. — For the 
preservation of good mental health the general health 
must be maintained by attention to all the laws of hy- 
giene. Muscular exercise is especially of the greatest 
importance to all classes of brain workers. The neglect 
of muscular exercise is much oftener responsible for the 
break-down of students and professional men than too 
much mental work. The average student requires at 
least one or two hours of vigorous exercise daily. It 
will not do to neglect daily exercise, and then endeavor 
to atone for it by devoting a week once or twice a year 
to violent exertions. This sort of spasmodic exercise is 
often more harmful than beneficial. Exercise, like sleep 
and food, should be taken regularly and daily. 

SUMMARY. 

1. Exercise of brain and nerves is essential to mental and nervous 
health. 

2. Brain capacity, being limited, should not be wasted. 

3. Proper study strengthens the brain ; "cramming " weakens it. 

4. Mental work is healthful ; worry is exhausting. 

5. Prolonged mental or nervous excitement is exhausting. 

6. Eight hours' sleep are required. Children need more. 

7. Inhibition is an important function of the brain, especially in 
regard to moral acts. 

8. Stimulating and unwholesome foods injure the brain. 

9. Brain workers require physical exercise daily. 



CHAPTER XXX. 

EFFECTS OF ALCOHOL UPON THE BRAIN AND 
THE NERVES. 

As we have elsewhere learned, alcohol, when brought 
in contact with any of the delicate tissues of the body, 
produces serious results ; but it is in its effects upon the 
nervous system that the mischievous character of this 
fascinating drug is most clearly seen. In small doses 
alcohol seems to excite mental and nervous activity; 
but the close observer will note that under the influ- 
ence of alcohol, even in very small doses, the controlling 
power of the reason and the will are to some degree 
lessened. Under the influence of liquor, even to a slight 
degree, a man will speak with less care, precision, and 
prudence than when free from the drug. 

404. The Whiskey Flush.— One of the first effects 
observed after alcohol has been taken is flushing of the 
face. Not only the face and other parts of the skin, but 
the whole body, the brain, the muscles, all the internal or- 
gans, are flushed. This is due to the paralyzing influence 
of the drug upon the vaso-motor centres — those which 
govern the size of the small blood-vessels. The vessels, 
being no longer under control, relax and fill with blood ; 
and if the body is exposed to cold, the temperature soon 
falls below the standard of health, in consequence of the 
presence of so large a volume of blood at the surface of 
the body. 

A little later, the centres which are involved in reflex 



232 SECOND BOOK IN PHYSIOLOGY. 

action and in the regulation of muscular movements 
become affected ; the underlip falls, the tongue becomes 
thick, the limbs totter, and the walk is irregular. Pres- 
ently the mind begins to exhibit the baneful effects of 
the poison. The higher faculties of the brain lose their 
control over the lower faculties. The will is paralyzed. ' 
The animal nature, freed from restraint, sometimes takes 
full possession of the individual, and the man becomes, 
for the time being, a brute. Still the drug continues its 
poisonous influence until all the faculties are benumbed 
and paralyzed. The drinker is now insensible, and is 
said to be " dead drunk." 

A person who is dead drunk is but a hand's-breadth 
removed from actual death. All the vital functions are 
nearly paralyzed. Any small circumstance, as exposure 
to a little extra cold or heat, may be sufficient to snuff 
out the flickering flame of life. It is asserted by some 
authorities that a man who has once been dead drunk 
never fully recovers from the effects. The idea that al- 
cohol protects a person from any of the causes of disease 
is a very grave and mischievous error. It undoubtedly 
increases the liability to disease of nearly every sort, and 
greatly increases the fatality of most diseases. 

The alcohol gradually escapes from the body through 
the lungs, skin, and other eliininative organs, and, after 
a few hours, sensibility and consciousness return ; but 
some time elapses before the individual fully recovers 
from the effects of the poisoning to which he has been 
subjected. The nerve tone is greatly lowered, the hands 
tremble, the head aches, the mind is confused, and there 
is so great depression of spirits that the drinker feels com- 
pelled to resort again to alcohol to relieve his sufferings, 
and thus the habit is continued. 



EFFECTS OF ALCOHOL UPON THE BRAIN, ETC. 233 

405. Alcoholic Nervousness. — The habitual use of 
alcohol, even in quantities not large enough to cause 
intoxication, often produces permanent results similar 
to those following a single large dose. By degrees the 
nerve centres lose their tone, and the hand becomes 
habitually unsteady, except when the system is under 
the influence of liquor. The flushed face, red eyes and 
nose, exhibit the paralyzed condition of the vaso-motor 
nerves. The mind becomes less acute and active, and 
the character is changed for the worse. 

406. Alcoholic Insomnia (Sleeplessness). — The 
blood-vessels of the brain, under the influence of alcohol, 
become relaxed, as do those of the face. The excess of 
blood in the brain keeps up an unnatural, though ineffi- 
cient, activity, and the man who at first took his even- 
ing dram as a " nightcap," to make him sleep, after a 
time finds himself wholly unable to sleep ; or, if he falls 
asleep, he is constantly awakened by frightful and dis- 
tressing dreams. 

407. Delirium Tremens. — The hard drinker some- 
times so completely exhausts his nervous system that 
reason becomes temporarily dethroned. The hobgoblins, 
grinning fiends, and hideous reptiles which formerly 
haunted his restless, unrefreshing sleep, take possession 
of his waking hours. Everything about him seems alive. 
Each familiar object appears to him like a furious beast 
ready to seize upon him. His most trusted friends are 
transformed into enemies. His countenance, haggard 
with disease and want of sleep, with staring, bloodshot 
eyes starting from their sockets, glancing this way and 
that as new and still more frightful shapes arise, depicts 
in every line a horror indescribable, while every muscle 
quivers and every nerve fibre seems a thread of fire. 



234 SECOND BOOK IN PHYSIOLOGY. 

One glimpse of a victim of delirium tremens would be 
a better temperance lesson than any pen could write. 
Not infrequently the poor victim's sufferings end only 
with death — a death of shame. 

408. Changes in Nerve Cells and Fibres pro- 
duced by Alcohol. —The first effects of alcoholic drinks, 
like those of most other poisons, are quite readily recov- 
ered from if the doses are small and not often repeat- 
ed ; but when long used, or when used in large doses, 
and in many persons even in doses called moderate, the 
nutrition of the nerve structures is impaired. The brain, 
receiving one-fifth of all the blood in the body, receives 
with its large blood supply an equally large proportion 
of the alcohol which may be taken, and hence is among 
the first of all the organs of the body to suffer from 
its effects. The connective tissue which holds its deli- 
cate cells and fibres together is stimulated by the irri- 
tation of the alcohol to abnormal growth, and after- 
wards contracts upon them, thus crippling or destroying 
them. 

Paralysis of various organs, and even of the whole 
body, is a not uncommon result of the degeneration of 
nerve structures caused by alcohol. The use of strong 
liquors is the frequent cause of locomotor ataxia — a dis- 
ease which is seldom cured. The victim of this malady 
walks all the time much like a man who is intoxicated. 
His nerve centres have been temporarily paralyzed so 
many times by alcohol that they have finally been 
damaged to such a degree that they remain permanently 
paralyzed. At first only the legs are affected. By- 
and-by the hands become equally unsteady, so that the 
afflicted person cannot feed himself. If the miserable 
man lives long enough, he finally becomes unable to 



EFFECTS OF ALCOHOL UPON THE BRAIN, ETC. 235 

swallow. His whole body is paralyzed, and lie dies a 
most horrible death. 

Sometimes the nerve structures undergo a change in 
which their essential parts are replaced by fat, resulting 
in various forms of paralysis. By its destructive effects 
upon the nervous system, which controls and regu- 
lates the entire body, the mischievous influence of al- 
cohol is made universal in the body, aside from its di- 
rect effects upon other tissues, which have been studied 
elsewhere. 

409. Alcohol not a Stimulant. — If by a stimulant 
we mean something that gives strength, then alcohol 
cannot be considered a stimulant. It certainly does not 
strengthen either the nerves or the muscles. Its real 
effect is that of a narcotic ; it benumbs and paralyzes. 
It produces a sensation of strength by destroying the 
sensation of fatigue, but it does not give strength. 
One might as well inhale ether or chloroform, or take 
strychnia or arsenic, for the purpose of gaining strength, 
as to take alcohol. 

410. Effects of Alcohol upon the Character. — Al- 
cohol lowers moral tone as well as nerve and mental 
tone. The moral sensibilities of the drunkard are blunt- 
ed. When under its influence sin does not seem so sinful, 
crime so criminal, nor dishonor so dishonorable as be- 
fore, and his weakened will leaves the victim of intem- 
perance an easy prey to vice and crime of every sort. 
Men go down the scale by degrees : first, the social 
glass occasionally ; then the regular dram ; then the 
loss of moral sense, self-respect, and respect for the 
rights of others ; and, finally, the commission of some 
dreadful crime under the influence of liquor. The loss 
of will-power, of self-control, caused by so often yield- 



236 SECOND BOOK IN PHYSIOLOGY. 

ing to temptation, as well as by the direct influence of 
the drug, is the great obstacle that stands in the way 
of the reformation of the drunkard and the victims of 
all vice-drugs. 

411. The Alcohol Legacy. — Not the least of the 
many grave charges which science brings against the al- 
cohol habit is the fact that its effects do not stop with 
the user ; they are transmitted to his innocent children. 
A child may inherit from a drunken parent an almost 
irresistible appetite for drink, together with a weakened 
will, so that it will almost certainly become a drunkard. 

This is not, however, the most common inherited ef- 
fect of the liquor habit. It has been observed by phy- 
sicians that the children of drinking parents inherit a 
tendency to epilepsy, or " falling-sickness," to idiocy, and 
especially to insanity. Dr. Hurd, the late superintend- 
ent of the Eastern Michigan Insane Asylum, has made 
a careful investigation of this subject, and finds that, in 
the cases of a very large proportion of the insane, one 
or both parents were given to drink. The " insane tem- 
perament " is often transmitted, even when the parent 
has shown no symptom of insanity except when under 
the influence of liquor. 

The reason for this is plain when we reflect that the 
different stages of the mental disturbance which results 
from taking a full dose of alcohol correspond exactly to 
the different phases of insanity. In fact, a man under 
the influence of liquor may be said to be insane just to 
the extent of the influence of the drug upon him. After 
many repetitions of the intoxication, an impression is 
made upon the brain and nervous system which may be 
inherited by a child as a tendency to insanity that may 
develop at any time of life. 



EFFECTS OF ALCOHOL UPON THE BRAIN, ETC. 237 

412. Moderate Drinking Dangerous. — Most of the 
effects which have been described are those which result 
from the use of alcohol in quite large quantities. Nev- 
ertheless, it cannot be denied that while alcohol may 
sometimes be used in small quantities for many years 
without producing very noticeable effects, there are 
very few persons indeed who can use it for any great 
length of time without increasing the dose to an amount 
which is harmful to a degree at once apparent. The 
advocates of moderate drinking must admit that alcohol 
is not naturally demanded by the system, and that its 
use is both unnecessary and dangerous, even for those 
who desire to restrict its use to a moderate allowance. 
It possesses no good property which we might not easi- 
ly do without, or find in less dangerous substances, and 
involves many and grave possibilities of evil. 

413. The Effects of Tobacco upon the Nerves — 
Every one is familiar with the tremulous hand of the 
smoker. Many persons whose business requires a steady 
hand have been compelled to renounce the use of tobacco 
on this account. When the hand trembles, the difficulty 
is not in the hand, but in the nerve centres which con- 
trol the muscles of the hand. If we examine the pulse 
of such a person, we often find that the heart trembles 
as well as the hand ; that is, it does not beat regularly, 
is subject to palpitations, and sometimes to paroxysms 
of pain. (See cut on page 121.) All this comes from 
the same cause, the poisonous influence of nicotine upon 
the nerve cells. 

The wide prevalence of tobacco using is unquestion- 
ably one of the causes of the great increase of nervous 
disorders among men. Various forms of nervous dis- 
ease have been traced directly to the use of tobacco, and 



238 SECOND BOOK IN PHYSIOLOGY. 

at the present time the most scientific physicians con- 
demn it as a harmful practice. 

The moral effects of tobacco using are certainly bad. 
A boy who smokes or chews associates with other boys 
who do likewise, among whom he is sure to find com- 
panions of the worst habits. Tobacco using also leads 
to the liquor habit, by creating nervous symptoms from 
which alcoholic drinks seem to give temporary relief. 

414. Tobacco and the Brain. — Some years ago an 
investigation was made in the public schools of France, 
which resulted in the prohibition of the use of tobacco 
by all students in the schools. Dr. Seaver, of Yale 
University, has shown that students who use tobacco 
are inferior to those who do not, both physically and 
mentally. The sale of tobacco to boys has been pro- 
hibited by law in several States of this country The 
bad effects of tobacco using are so well recognized in 
Switzerland that very strict laws have been made 
against it. A boy found smoking upon a street in that 
country is promptly arrested by the police. 

415. Cigarettes. — The use of cigarettes by boys and 
young men, which is becoming so common, is worthy of 
strongest condemnation. This method of taking tobacco 
is the most pernicious of all. Deaths from cigarette 
smoking are frequently reported. The writer has met 
many cases in which young men have been ruined men- 
tally, as well as physically, by the use of cigarettes. 

416. Hereditary Effects of Tobacco Using. — 
While the hereditary effects of tobacco using are not so 
apparent as those which follow the use of alcohol, there 
is good ground for believing that the free use of tobacco 
may so injure the nervous system that children may suf- 
fer through inheriting a tendency to nervous diseases. 



EFFECTS OF ALCOHOL UPON THE BRAIN. ETC. 239 

There is no excuse for the use of tobacco which will 
not also apply equally well to the use of opium, alcohol, 
or any other narcotic. 

417. The Opium Habit. — The increase in the use of 
opium has been so enormous within the last few years 
as very justly to excite alarm among all who are inter- 
ested in the welfare of the race. Of all drugs, opium is 
perhaps the most fascinating, and the habit of using it 
the most difficult to overcome. The ease and comfort 
afforded by it, when painful disease is present, allures 
the victim into the acquirement of a habit which ulti- 
mately ceases to give pleasure, or even to relieve suffer- 
ing, and renders its victim most miserable. 

The opium habit is usually acquired by the use of the 
drug to relieve pain, either in the form of opium itself 
or any one of its various preparations, the most common 
of which are morphia, laudanum, and paregoric. Often 
it is first taken by prescription of a physician, and is 
continued by the patient. Many patent medicines con- 
tain opium, as do most of the cough mixtures, " soothing 
syrups," etc. These nostrums are very dangerous, and 
should never be used. 

Opium in any form should never be used without the 
advice of a reliable physician, who appreciates the dan- 
gers from the use of the drug, as well as the possible 
benefits to be derived from it. 

Opium, when habitually used, ruins the nervous sys- 
tem and the mental and moral faculties. Self-control 
and self-respect are lost. Reputation, honor, friends, 
wealth — everything is sacrificed for the gratification of 
the artificial appetite which has been established. The 
victim finds that, when he attempts to discontinue its 
use, he is overwhelmed with untold sufferings the mo- 



240 SECOND BOOK IN PHYSIOLOGY. 

ment the influence of the drug is gone. Prostrated 
with indescribable weakness and faintness, distracted 
with excruciating pain, it is no wonder that he returns 
again to the only source of immediate relief. These 
miserable beings are greatly to be pitied, and their hor- 
rible experience should be a warning to those who are 
yet free from the snare. 

Any one who has ever seen the besotted opium- 
smoker indulging his vice in one of the horrible opium 
dens of China or San Francisco, will be surprised to 
learn that this dreadful practice is being adopted by 
Americans and Europeans. In both New York and 
London these dens are frequented by a considerable 
number of persons who have acquired the practice since 
its introduction into these cities by the Chinese, and the 
number is said to be increasing. 

418. Chloral and Kindred Drugs. — Hydrate of 
chloral, bromide of potassium, and other sleep-producing 
and nerve - benumbing drugs, are very largely used in 
patent medicines, and not infrequently by persons who 
have learned their use from popular medical works. It 
ought to be generally known that the sleep produced by 
these drugs is not healthful, refreshing slumber, but is 
what an eminent physician has well called " poison sleep," 
— a state in which the sensibilities are benumbed into 
unconsciousness, but in which the natural processes of 
repair and storing up of nervous and vital energy are 
not properly performed. 

Narcotic drugs relieve pain, but do not remove its 
causes. A pain of which we are made unconscious by a 
stupefying drug is still present in nearly full force, so 
far as the system is concerned, although we are not con- 
scious of it ; just as a man whose limb is amputated 



EFFECTS OF ALCOHOL UPON THE BRAIN. ETC. 241 

while he is insensible from chloroform feels no pain, 
although the tissues are hurt just as much as if he did. 
Any drug of this class, used habitually, causes serious 
disorders, and generally disturbs the digestion, as well 
as nearly every other vital process in the body. 

410. Tea and Coffee. — By far the most common cause 
of " nervous " and " sick " headaches, ailments which tea 
is supposed to be most potent in relieving, is the use of 
this very beverage. Much of the nervousness, neural- 
gia, nervous dyspepsia, and sleeplessness among women 
is recognized by observing physicians to be due to the 
use of tea and coffee. 

There are many, even among physicians, who are 
ready to apologize for the use of tea and coffee, and un- 
doubtedly some persons use these drugs in quantities so 
moderate that no serious effects are felt ; but the fact 
that they are potent for harm, and that an immense 
amount of injury is done by their use, ought to be gener- 
ally known. We may well dispense with the use of ar- 
ticles which, under the deceptive guise of "the cups that 
cheer, and not inebriate," have captivated nearly the en- 
tire civilized world. 

Dr. Xansen, the eminent Arctic traveller, states that 
the Esquimaux of the east coast of Greenland, being un- 
able to obtain alcoholic drinks, w^hich are strictly forbid- 
den by the Danish Government, use strong coffee in large 
quantities and become deeply intoxicated by it, and with 
most disastrous effects. Dr. Nansen asserts that coffee 
is a great curse to the Esquimaux. 

420. Cocaine. — This new vice-drug is most deadly 
and destructive in its effects. The immediate effects of 
its use are similar to those of opium, but more transient. 
The health, physical and mental, rapidly succumbs to its 



242 SECOND BOOK IN PHYSIOLOGY. 

influence, and insanity and death speedily follow, The 
general use of this drug in diseases of the eye and the 
nose has led many to become victims of its fascinating 
influence. The cocaine-habit is more difficult to over- 
come than the use of either opium or alcohol. 

421. The Poison -Habit. — The use of alcohol, to- 
bacco, opium, cocaine, and various other kindred drugs 
produces in the user a morbid condition in which there is 
an abnormal craving for some agent which will benumb 
sensibility, or temporarily produce a pleasurable sensa- 
tion. This condition, when once established, is exceed- 
ingly difficult to overcome, and leads the unfortunate 
victim of the poison-habit to seize upon any drug which 
will afford him temporary relief from the horrible ner- 
vousness to which he is a constant prey, or which will 
serve as a nerve-tickler to give him some sensation which 
habit has led him to consider pleasurable. It is for this 
reason that we seldom find the victim of the poison-habit 
using only a single drug. The man who is addicted to 
the use of liquor almost invariably uses tobacco also, 
and not infrequently opium is added to the twin poisons 
mentioned. Women who drink strong tea and coffee 
not infrequently find it necessary to resort to the use of 
chloral and opium to relieve the nervousness produced 
by these drugs ; and it is an easy step from tea and 
coffee inebriation to the use of wine and brandy when 
occasion requires an extra strong " pick-me-up." 

By the use of these drugs the nutrition of the body 
becomes so much impaired that its very structure is 
changed. The nervous system is particularly subject 
to these functional disturbances and structural changes. 
The brain, the organ of the mind, receiving a large pro- 
portion of all the blood of the body, is especially affected 



EFFECTS OF ALCOHOL UPON THE BRAIN, ETC. 243 

by these poisonous drugs. The character of the indi- 
vidual is seriously modified and impaired. The use of 
alcohol, for example, weakens the will of the user. The 
tobacco devotee, as a rule, through his habit becomes 
selfish, and loses his nice sense of propriety and cleanli- 
ness. The opium user becomes untruthful, and in many 
other respects unreliable. 

The growth of the poison-habit in this and other civ- 
ilized countries is coming to be one of the greatest of all 
the scourges of civilization. It is not safe to trifle with 
any of these drugs, since the habit of their use, while 
easily acquired, often fastens itself upon the victim with 
such unyielding tenacity that escape becomes impossible. 
Thousands of boys, and sometimes girls also, have been 
ruined by the habit of cigarette smoking. It has been 
recently shown that the manufacturers of cigarettes not 
infrequently put into them drugs more fascinating and 
poisonous than tobacco, thus securely fastening their vic- 
tims to the use of their own particular brand. 

SUMMARY. 

1. Alcohol lessens the inhibitory power of the brain, and hence 
weakens the will and injures the character. 

2. Hereditary effects of alcohol — insanity, nervous diseases, and the 
liquor habit. 

3. Tobacco lessens mental vigor and occasions many nervous disor- 
ders. 

4. Strong tea and coffee cause nervous disease. 

5. Opium and chloral destroy both mind and body. 

6. Cocaine is the most deadly and fascinating of all vice-drugs. 

7. The poison-habit produces effects which are not only destructive 
to the individual, but may be transmitted by heredity. 



CHAPTER XXXI. 
THE SPECIAL SENSES.— THE SENSE OF TOUCH. 

422. What is Sensation ? — Sensation is the result of 
a change in the condition of a sensitive part. When an 
object is brought into contact with the skin, it is at first 
distinctly felt ; but if the contact is maintained for some 
time, we cease to realize the presence of the object, and 
remain unconscious of its presence until it is removed. 

423. Two Kinds of Sensations. — There are two 
kinds of sensations : 1. Those which inform us concern- 
ing conditions within the body, as pain, hunger, thirst, 
satiety, nausea, giddiness, fatigue, and drowsiness, which 
are called general sensations. 2. Those by means of which 
we obtain a knowledge of the properties of external 
objects, as sight, hearing, smell, taste, touch, the sense of 
temperature, and the sense of weight, which are called the 
special senses. 

Pain is produced by injury to the tissues, and by 
excessive stimulation of any of the senses, even those 
which are ordinarily most pleasurable. A very bright 
light pains the eyes ; a very loud sound is painful to the 
ears. Pain is one of the most useful of all sensations. 
It often preserves the body from serious injury, acting 
as a sentinel to give warning when harm is threatened. 

The sense of touch is located in the skin, and in por- 
tions of the mucous membrane near the openings of the 
body. It is most acute in the ends of the fingers, the 



THE SPECIAL SENSES.— THE SENSE OF TOUCH. 245 

lips, and the tip of the tongue. By its aid we are able 
to distinguish the form of objects, and whether they are 
hard or soft, rigid or elastic, etc. (See Experiment 22, 
page 276.) 

The sense of space, or locality, is probably a modifica- 
tion of the sense of touch. Through its aid we are able 
to determine the part of the body touched by any ob- 
ject. There is great difference in the acuteness of this 
sense in different portions of the body. 

By the sense of pressure we are able to distinguish 
between the weights of two objects allowed to rest 
upon the same spot, one immediately after the other. 
This sense is a modification of the sense of touch. 

The delicacy of the sense of touch and of its various 
modifications may be greatly increased by education. 
In the blind it is often extraordinarily acute. 

The sense of temperature is another so-called modifi- 
cation of the sense of touch, although it is probable that 
it requires a separate set of nerves. This sense enables 
us to determine the temperature of objects, or to distin- 
guish between heat and cold. The temperature sense 
is largely relative, giving us an idea of the difference in 
temperature between the object touched and the part 
of the body, touching it, rather than of absolute tem- 
perature. The mucous membrane is less sensitive to 
heat and cold than is the skin. 

The muscular sense, or the sense of weight, enables us 
to determine the amount of exertion required in lifting 
and other muscular efforts. It also tells us of the rapid- 
ity with which the muscles contract, and of the position 
of the limbs of the body. Though probably an inde- 
pendent sense, and located in the muscles, the sense of 
weight is closely allied to that of touch. 



246 SECOND BOOK IN PHYSIOLOGY. 

424. Effects of Alcohol. — The paralyzing effect of 
alcohol is well shown by its influence upon the sense 
of touch. A few drops of alcohol applied to the end 
of the tongue destroy its marvellous delicacy of touch. 
When taken in large doses, alcohol produces as pro- 
found insensibility to pain as does ether or chloroform. 
It was used as an anaesthetic in surgical operations be- 
fore the discovery of chloroform and ether, but its use 
was discontinued on account of the effect upon patients 
in delaying their recovery and increasing the risks of 
serious operations. 

In some experiments recently made by the author for 
the purpose of ascertaining the effect of alcohol upon 
the nervous system, it was noticed that the- sense of 
touch was diminished more than one-half as the result 
of taking two ounces of whiskey. Before taking the 
Avhiskey the subject of the experiment was able to recog- 
nize the contact of an object with the skin in one-seventh 
of a second. A short time after taking two ounces of 
whiskey the delicacy of the sense of touch was diminished 
to such a degree that more than twice as long was re- 
quired for the recognition of the contact with the skin. 
The same series of experiments showed that the sense 
of temperature and other modifications of the sense of 
touch were equally diminished by alcohol. 

SUMMARY. 

1. The sense of touch is located in the skin, and in the mucous 
membrane near the openings of the body. 

2. The senses of space or locality, of temperature, and of pressure, 
are closely related to the sense of touch. 

3. The muscular sense, or sense of weight, resides in the muscles. 

4. The delicacy of each of these senses may be greatly increased by 
education. 

5. Alcohol benumbs the sense of touch ; it is an anaesthetic. 



CHAPTER XXXII. 
THE SENSE OF SMELL. 

The nerves of smell, or the olfactory sense, is located 
in the mucous membrane of the upper portion of the 
nasal cavity. The ends of these nerves are bare, so that 
the odorous particles by which they are excited may 
come into immediate contact with them. 

In order that the sense of smell shall be exercised, the 
odorous substances must be brought to the nose by the 
air, the mucous membrane must be moist, and the air 
must be drawn through the nose. When the nose is 
obstructed, as by a cold, the sense of smell is greatly 
lessened or lost. Odorous substances are smelled when 
held in the mouth, the odorous particles being carried 
through the nose by the outgoing breath. This often 
leads us to ascribe to substances flavors which are real- 
ly odors. 

425. Acuteness of the Sense of Smell. — Theacute- 
ness of this sense is so great in healthy persons that so 
small a proportion as one-millionth part of a grain of 
some substances may be easily detected in the air of a 
room. 

The mucous membrane of the nose possesses gener- 
al sensibility, the same as other portions of the body. 
Many of the sensations experienced through the nose? 
and commonly called odors, are those of pain rather 
than of smell. The inhalation of ammonia, and of most 



248 SECOND BOOK IN PHYSIOLOGY. 

other irritating gases, excites the nerves of pain and not 
the olfactory sense. 

426. Use of the Sense of Smell. — This sense may 
be of service to us in determining whether substances are 
fit for food ; it also warns us of the danger of inhaling 
poisonous gases. It is a noteworthy fact that among 
natural odors — that is, such as an uncivilized man would 
come in contact with — those which are offensive are con- 
nected with poisonous or unwholesome substances. 

427. Hygiene of the Sense of Smell.— As just inti- 
mated, offensive odors are to be regarded as unwholesome. 
Nature has wisely placed this danger-signal at the very 
portal of the body, and its warning should always be 
promptly heeded. If disregarded, odors which are at 
first very offensive are soon tolerated, and after a time 
are no longer observed. 

Strong Odors of any sort are objectionable, as they 
are usually produced by volatile substances which are in- 
jurious if taken into the system in any but the most mi- 
nute quantities. This, also, nature hints to us in causing 
the most agreeable odors to become disgusting when in- 
haled in too concentrated a form. 

The sense of smell is sometimes more or less com- 
pletely lost, as the result of frequent and neglected 
colds, which may destroy the sense of smell by causing 
obstructions of the nasal passages, so that odors cannot 
reach the olfactory nerves, or may even destroy the 
nerves themselves. 

428. The Effects of Tobacco and Alcohol upon 
the Sense of Smell. — The abominable habit of snuff- 
taking is fatal to the sense of smell. Smoking, espe- 
cially cigarette-smoking, is often a cause of the loss of 
this useful sense. The tobacco -user is also a source of 



THE SENSE OF SMELL. 240 

offence to the noses of all people who do not defile them- 
selves with the filthy weed. No one whose ideas are 
not greatly perverted will be willing to saturate himself 
with a vile-smelling drug, against which Nature seeks to 
protect herself by destroying his sense of smell, but 
which makes him a nuisance to everybody else not in 
the same condition as himself. 

The alcohol -habit, as well as the tobacco -habit, is a 
means of destroying the sense of smell, exposing the user 
as it does to frequent colds by causing relaxation of the 
exposed blood-vessels so that they become easily chilled. 
The effect of alcohol in producing congestion of the nasal 
mucous membrane is indicated in a most positive manner 
by the redness of the face so often observed in chronic 
topers. The thickening of the skin of the face and the 
frequent enlargement of the nose commonly known as a 
u rum blossom " is associated with a similar thickening 
of the mucous membrane of the nose by which the nasal 
passages are closed, the delicate nerves of smell buried 
beneath a swollen membrane, and thus the sense of smell 
more or less completely obliterated. 

SUMMARY. 

1. The nerves of smell are located in the upper part of the nasal 
cavity. 

2. Many so-called odors are really sensations of pain. 

3. The object of the sense of smell is to warn us against poisouous 
and harmful substances. 

4. The nose soon becomes accustomed to bad odors ; hence, their 
first warning should be heeded. 

5. Strong odors, even at first agreeable, may become injurious. 

6. Repeated colds destroy the olfactory sense. 

7. Snuff-taking and cigarette-smoking destroy the sense of smell. 



CHAPTER XXXIII. 
THE SENSE OF TASTE. 

The nerves of taste are located in the sides and back 
of the tongue, in the soft palate, and in the upper part 
of the throat. There are three distinct nerves of taste, 
which are distributed to different parts of the tongue. 

429. The Tongue is a muscular organ, and one of 
the most remarkable in the body, being capable of won- 
derfully rapid and varied movements. The mucous mem- 
brane which covers it presents on its upper surface many 
little prominences called papillae, in which nerves both of 
taste and of touch are distributed. 

430. How and What We Taste. — In order that a 
substance may be recognized by the tongue it must be 
soluble ; that is, it must dissolve in water. Substances 
which w T ill not thus dissolve have no flavor. The dis- 
solved substances soak through the thin layer of cells 
covering the ends of the nerves of taste, and thus excite 
sensation in them. 

Although we recognize a great variety of flavors, the 
majority of so-called tastes are combinations of tastes, 
odors, and impressions of touch. 

The sense of taste does not seem to be equally dis- 
tributed over the surface of the tongue. With the ex- 
treme tip of the tongue we really do not taste at all, 
but only feel. The nerves of pain and touch found here 
are exceedingly delicate and acute. Pungent, acid, alka- 
line, astringent, and saline flavors are recognized by the 



THE SENSE OF TASTE. 251 

tij) of the tongue. The flavor of such substances as 
mustard, pepper, cinnamon, etc., is due to the feeling 
which they excite, combined with the odor of aromatic 
oils which they contain, and which the olfactory nerves 
detect in the breath when exhaled through the nose. 
This explains why the so-called taste of mustard, pepper, 
cinnamon, and similar substances is so much like their 
corresponding odors. 

The pungent flavor of pepper, mustard, and similar 
substances, as well as the burning taste of alcohol, must 
be regarded as Nature's warning voice, saying, " This 
article is not good." 

Sweet and bitter are recognized by the central por- 
tion of the tongue. The back part of the tongue and 
the throat recognize that peculiar class of tastes which 
produce the sensation of disgust when strongly excited, 
as in partaking too freely of fats, oils, animal foods, and 
rich pastries. The nerves which preside over this depart- 
ment of the sense of taste are in close sympathy with the 
stomach. This fact explains the nausea which is often 
produced by too rich foods. 

431. Uses of the Sense of Taste. — One important 
object of the sense of taste is to inform us whether sub- 
stances taken into the mouth are wholesome or poisonous. 
As a general rule, substances which have an agreeable 
flavor are good for food. This is at least true of natural 
productions. The poisonous parts of noxious plants have 
disagreeable and repulsive flavors, as do the poisonous 
parts of some edible plants — for example, the seed-balls 
of the potato-plant. 

Another very important use of flavors is to excite the 
activity of the glands which secrete the digestive fluids, 
and to produce a relish for food. Substances which have 



252 SECOND BOOK IN PHYSIOLOGY. 

no flavor are insipid, and are rejected as food by most 
lower animals, as well as by man. Such substances, al- 
though wholesome, are often digested less readily than 
those which have decided flavors. 

432. Hygiene of the Sense of Taste.— Condiments 
and all substances which produce a smarting sensation 
when applied to the tongue injure the nerves of taste, 
and destroy their ability to recognize delicate flavors, 
besides, as has been pointed out elsewhere, doing harm 
in various ways to the nervous system and the digestive 
organs. This class of substances is rejected by an un- 
perverted taste. 

433. Alcohol and Tobacco. — Strong liquors para- 
lyze the nerves of taste. A teaspoonf ul of alcohol held in 
the mouth for a few minutes will so benumb the nerves 
that ordinary flavors cannot be perceived. The habitual 
use of strong liquors permanently injures this delicate 
and valuable sense. 

The use of tobacco has practically the same effect 
upon the sense of taste. A man who chews or smokes 
tobacco cannot distinguish delicate flavors. On this ac- 
count tea-tasters are obliged to abstain from the use of 
the weed. Is it not an outrage against our bodies to 
destroy the delicate sensibilities with which we are en- 
dowed, and in so doing deprive ourselves of the protec- 
tion which these vigilant sentinels afford, at the same 
time inflicting upon other delicate organs of the body 
injuries which obedience to the dictates of our natural 
instincts would prevent ? 

It is a mistake to suppose that by the use of tobacco, 
alcohol, or any other narcotic or stimulant one really adds 
to the enjoyments of which the body is capable. When 
first used these drugs afford a certain pleasure of a low 



THE SENSE OF TASTE. 253 

type; but after one becomes accustomed to their use 
they no longer excite pleasure, but are used rather to re- 
lieve discomfort or actual pain than to produce pleasur- 
able sensations. The particular drug habitually used 
becomes necessary to make the user comfortable without 
giving him pleasure. Thousands of those who use nar- 
cotic and intoxicating drugs, such as alcohol, opium, and 
tobacco, would gladly rid themselves of the bondage of 
a habit contracted in youth when ignorant of its evil 
effects. 

The popular idea that tobacco is a cleansing agent, 
that it disinfects the mouth, and thus in some way con- 
tributes to the health of the user, is in the highest degree 
erroneous. The benumbing influence of this drug upon 
the nerves of taste is a good illustration of the poisonous 
influence which is exerted upon all living cells and upon 
every tissue and structure of the body. It not only in- 
jures the nerves of taste, but all other senses with which 
it comes in contact in the mouth, and extends its baneful 
influence to the whole body as well. 

SUMMARY. 

1. The nerves of taste are located in the tongue and pharynx. 

2. Substances must be soluble in order to be tasted. 

3. Most so-called tastes are combinations of the sense of taste with 
those of touch and smell. 

4. The object of the sense of taste is to inform us whether articles 
taken into the mouth are unwholesome or poisonous. 

5. Substances which have an unpleasant or pungent taste are usu- 
ally harmful. 

6. Condiments injure the sense of taste as well as the digestive or- 
gans, and are rejected by a healthy taste. 

7. Alcohol and tobacco greatly impair the sense of taste. 



CHAPTER XXXIV. 
THE SENSE OF HEARING. 

434. The Simplest Ear. — The organ of hearing is 
the ear. We can best understand the structure of this 
remarkable organ by first studying the ear in its simplest 
form. Such an ear is found in the barnacle, a small 
creature often found adhering to ships' bottoms, and to 
piers and other objects immersed in sea-water. Near 
the mouth of this little animal is found a small opening 
leading into a cavity running upward. From the top of 
this chamber hangs a minute sac filled with fluid, on the 
walls of which are spread out many delicate nerve fibres. 
This is the barnacle's ear. The ear of a lobster is much 
like it, only the little sac is lined with cells having deli- 
cate hairs which extend into the fluid, among which are 
numerous little grains called ear-stones. 

435. The Ear of a Fish. — In a fish the little sac has 
connected with it three membranous canals, each like a 
half -circle in form, whence they are called semicircular 
canals. Each canal communicates with the sac by both 
its ends. From this fact the sac is termed the vestibule, 
or common hall. Both the vestibule and the semicircu- 
lar canals are filled with fluid and lined with cells, some 
of which are hairy. The vestibule contains two or three 
ear-stones, which in some large fishes are an inch in 
length. The vestibule and semicircular canals are to- 
gether called the labyrinth. The whole labyrinth is 



THE SENSE OF HEARING. 255 

enclosed in a cavity in the skull of the fish, and is at- 
tached to one side of it. From an external examination 
a iish appears to have no ears, as its ears have no exter- 
nal opening. 

In a snake the bony cavity enclosing the labyrinth is 
connected with the skin by a little bone. In the turtle 
this little bone is enclosed in a second cavity in the skull, 
the outer end of which is closed by a membrane, thus 
forming a sort of ear-drum, the head of which is con- 
nected by the bone with the labyrinth in the inner cav- 
ity. The drum-head of the turtle's ear lies just under 
the skin. 

436. The Human Ear. — The ear of man is essentially 
like that of these lower animals, only more perfect. It 
has, in addition, an external part composed of skin and 
cartilage, which aids in the concentration of sounds. It 
also has an addition to the labyrinth — a shell-shaped 
cavity called the cochlea, from its resemblance to a snail- 
shell. The cochlea contains a great number of nerve 
fibres of different lengths. In the human ear, also, the 
little bone found in the drum cavity is divided into three 
separate bones, the incus (anvil), the malleus (mallet), 
and the stapes (stirrup). The labyrinth contains minute 
ear-stones similar to those of the barnacle. 

It thus appears that the perfect ear consists of three 
portions : the large outer portion, or external ear, a drum 
cavity, or middle ear, and the labyrinth, or internal ear. 

Connected with the bones of the middle ear, in man, 
are two very minute muscles. The drum cavity is con- 
nected with the back of the throat by a small tube, the 
Eustachian canal. 

From this comparative study of the structure of the 
ear, it is apparent that the most essential part of this 



256 



SECOND BOOK IN PHYSIOLOGY. 




remarkable organ is the labyrinth, or internal ear, in 
which the nerve of hearing is distributed. This struct- 
ure is found in some form, in all animals that can hear, 

from man down to 
the humble barnacle. 
The other portions of 
the ear are added in 
man and the higher 
animals, to render 
the hearing more per- 
fect. 

437. How We 
Hear. — Best one end 
of a board • upon a 
table, holding it in po- 
sition by the left 
hand. Now, with the 
right hand, draw a 
pin across the board. 
It will be noticed that 
the board vibrates or trembles. Now press the side of 
the head against the upper end of the board and draw the 
pin across it again. A loud sound will be heard. This is 
because the vibrations or tremblings of the board have 
been communicated through the bones of the head to the 
internal ear, causing the fluid in the labyrinth to vibrate — 
which, in turn, causes vibration of the delicate hairs which 
hang out from the cells. By this means an impression is 
made upon the nerves of hearing, which, when conveyed 
to the brain, is recognized as sound. It is in this manner 
that the fish is able to hear with no external ear, sounds 
being conveyed to its ears through the bones of its skull. 
We are able to hear the scratching of the pin, although 



Fig. 45. — Section of the Ear. 
1. External Canal ; 2. Drum-head; 3. Ear Bones; 
4. Labyrinth; 5. Eustachian Canal. 



THE SENSE OF HEARING. 257 

less distinctly, even if we do not place the ear against 
the board. In this case the vibrations of the board cause 
vibrations of the air, or sound waves, which are brought 
to the external ear, gathered by it, and transmitted by 
the drum-head and the little ear-bones to the fluid in 
the labyrinth, and thus to the nerves of hearing. All 
sounds are produced by vibrations of some sort. 

The lowest musical note is produced by about sixteen 
and one-half vibrations per second, the highest by about 
fifty thousand vibrations. In some persons the musical 
part of the ear seems to be defective, while in others it 
has by cultivation been made so acute as to enable them 
to distinguish between notes having a difference of but 
one hundredth part of a tone. 

The sense of equilibrium is supposed to reside in the 
semicircular canals. It has been found that if a certain 
part of the canal is injured in some lower animals, the 
creature will roll over and over constantly. Injury to 
another part will cause the animal to turn somersaults. 

The object of the Eustachian tube is to allow a change 
of the air in the drum cavity, so as to keep it of about 
the same density as the air outside the body. 

The air in the ear may be changed by a simple method 
which may sometimes be usefully employed. Grasp the 
nostrils between the thumb and finger so as to close the 
nose tightly. Take a full breath, and, closing the mouth, 
attempt to blow through the nose. The air, not being 
able to pass through the usual channel, is by the pressure 
forced up through the Eustachian canal to the middle ear. 
It does not pass through the ear unless the drum mem- 
branes have been ruptured by inflammation, a frequent 
result of scarlet-fever. If the membrane is perforated a 
whistling sound is often heard when the ears are inflated. 



258 SECOND BOOK IN PHYSIOLOGY. 

The inflation of the ears should not be repeated very fre- 
quently. If employed when the ears are " stuffed up " 
by a cold causing obstruction of the ear-tubes, it will fre- 
quently give relief and restore the hearing. Persons who 
work in diving-bells find it necessary to change the air 
in the ears, in order to prevent rupture of the membrane 
from the pressure of the atmosphere whenever the diving- 
bell is raised or lowered. 

The little muscles of the middle ear tighten and relax 
the drum-head, for the purpose of adjusting it to receive 
loud and soft, high and low sounds. 

The cochlea of the internal ear is supposed to contain 
that part of the nerve of hearing by which we distin- 
guish musical sounds. 

The canal of the external ear is studded with fine 
hairs, and lubricated by a viscid and very bitter sub- 
stance, commonly known as ear -wax. The object of 
both hairs and wax is to prevent the entrance of insects 
into the canal. 

438. How to Care for the Ears. — Observe the fol- 
lowing rules respecting the care of the ears : 

1. Never clean the ears with a pick or an ear-spoon. 
In health, the ear-wax dries up and falls out of itself. 
If ear-wax accumulates, the ears should be examined by 
an ear specialist. 

2. Never allow cold water to enter the ears, and do 
not let the cold wind blow into them. If cotton is 
placed in the ear, do not neglect to remove it as soon as 
it is not needed. 

3. To remove a foreign body, syringe the ear with 
warm water, leaning the head to one side, so that the 
object may drop out if loosened, and draw the ear 
upward and backward, to straighten the canal. If an 



THE SENSE OF HEARING. 259 

insect gets into the ear, pour in a little oil, which will 
suffocate it, when it may be removed by syringing. 

•i. Shouting into the ear may cause deafness. When 
a loud sound is expected, prepare for it by closing the 
mouth and covering the ears. 

5. Never box or pull the ears. Permanent deafness 
may result. 

6. A discharge from the ear may become dangerous 
to life. A physician should be consulted at once. 

7. Avoid the use of " catarrh " nostrums and ear medi- 
cines. 

8. A cold which causes partial loss of hearing should 
receive prompt attention. The foundation of incurable 
deafness is often caused in this way. Blowing the nose 
with great violence may result in injury to the ears. 

439. Tobacco and Ear Disease. — The use of tobac- 
co in any form often occasions deafness by causing 
disease of the throat or the nose, which leads to ear 
disease. The same may be said of the use of alcoholic 
liquors. Smoking, and especially the use of cigarettes, is 
exceedingly injurious to the ears, as is also that very 
unclean practice, the use of snuff. 

SUMMARY. 

1. The simplest ear is a little sac filled with fluid, on the walls of 
which are distributed the nerves of hearing. 

2. A perfect ear is composed of three parts: the external ear, the 
middle ear, or drum cavity, and the internal ear, or labyrinth. 

3. The internal ear is the essential organ of hearing. 

4. We ordinarily hear through vibrations of the air, called sound- 
waves. 

5. These waves cause vibration of parts of the middle ear, which 
communicate the impression to the nerves of hearing. 

6. The Eustachian tube, which connects the middle ear with the 
throat, provides for a change of the air in the drum cavity. 



CHAPTER XXXV. 
THE EYE, AND HOW WE SEE. 

440. The Simplest Eyes. — A polyp is able to see 
without eyes, or at least to recognize light, for it folds 
its arms when a cloud passes over the sun. A starfish 
sees by means of a little red spot containing nerve end- 
ings at the apex of each of its arms. A leech has a 

semicircular row of 
eight or ten eye -spots 
just above its mouth, 
which are much more 
satisfactory eyes. Each 
consists of a little spot 
of transparent skin, 
back of which is a lay- 
er of dark pigment, be- 
tween the two being 
spread out the ends of 
the fibres of a nerve of 
sight. The eye of a 
leech contains all the essential parts of an organ of 
sight, but its vision is very imperfect. 

In the higher animals and man the colored layer and 
the nerves of sight are spread out on the inside of a 
rounded cavity in the skull, the front side of which is 
closed by a transparent membrane. The centre of the 
cavity is filled with transparent substances, through 




Fig. 46.— The Eye. 
1. Iris; 2. Pupil. 



THE EYE, AND HOW WE SEE. 



261 



which the light passes. This is a general idea of the 
eye, but we must study it more minutely. 

In man the most important organs of sight are com- 
prised within the eyeball, which is nearly round, and is 
placed in a socket in the skull. It consists of the fol- 
lowing parts : 

441. Three Coats. — The eyeball presents three mem- 
branous layers or coats : 1. The outer coat, consisting 
of a dense white membrane, the white of the eye, or the 
sclerotic, which covers the entire eyeball, with the ex- 
ception of the trans- 
parent portion in 
front, the cornea. 2. 
The second coat, a col- 
ored layer, called the 
choroid, which lies 
in close contact with 
the outer coat at all 
places except just be- 
hind the cornea, where 
the iris, a movable 
muscular curtain lined 
with dark pigment, is 
substituted for it. The 




ins 



has 



an 



Fig. 47. — Section of the Eye-ball. 

1. Cornea; 2. Pupil; 3. Iris; 4. Crystalline Lens; 
5. Vitreous Humor; 6. Retina; 7. Choroid; 8. 
Sclerotic; 9. Optic Nerve. 



through its centre, the 

pupil. 3. The third, or nervous coat, called the retina, is 
spread out over the choroid, and lines the back part of 
the eyeball. 

442. The Retina. — The retina contains the nerves of 
sight. It is formed by the spreading out of the end of 
the optic nerve, which enters the eyeball at the back 
side, nearly opposite the pupil. The retina is composed 



262 SECOND BOOK IN PHYSIOLOGY. 

of several layers of different kinds of cells, which are 
connected with the ends of the fibres of the optic nerve. 
The layer of cells next the choroid has a purple color. 
The color fades w r hen the retina is exposed to light, but is 
constantly reproduced by the choroid. By means of the 
optic nerve, the retina is connected with the nerve centres 
of the brain which preside over the sense of sight. 

443. The Three Humors. — The greater portion of 
the cavity of the eyeball is filled by a transparent jelly- 
like substance, called the vitreous humor (1). The front 
part of the vitreous humor is hollowed out to receive a 
much harder, transparent body, shaped like a lens, and 
called the crystalline lens (2). The lens is enclosed in a 
sheath, or capsule, which is also transparent. Its border 
is surrounded by a muscular ring. The lens is placed 
just behind the iris. The space between it and the cor- 
nea is filled with the aqueous humor (3), a watery fluid 
which runs out when the eyeball is punctured by any 
sharp instrument. 

444. The Eye-socket. — The eye is placed, for safety, 
in a deep socket hollowed out in the skull, open in front, 
and communicating, at its back part, with the cavity 
of the skull by an opening through which pass the vari- 
ous nerves which connect the several parts of the eye 
with the brain. Lining the socket, and outside of the 
eyeball, is a quantity of fat, which acts as a cushion to 
protect the organ from the effect of jars. 

445. The Eyelids. — The eyelids are folds of skin 
which protect the front part of the eyeball. They are 
lined with a delicate mucous membrane, which extends 
over the front portion of the eyeball. Along the edge of 
each eyelid may be seen the openings of numerous little 
glands, which pour out upon the edge of the eyelids an 



THE EYE, AM) HOW WE SHE 203 

oily substance, which prevents the overflow of the tears. 
The edge of the lids is also furnished with a row of 
hairs, the eyelashes, the use of which is to keep dust out 
of the eyes, and, if the lids are partially closed, to pro- 
tect the eyes from too bright a light. 

440. The Tear-gland and Ducts. — Within the sock- 
et of the eye, and at its outer and upper side, is placed 
a little gland which produces the tears. This secretion 
is constantly formed in small quantity for the purpose of 
moistening the eye. The secretion is drained away by 
means of two little canals, one opening at the edge of 
each lid, near the inner corner of the eye. The two 
canals open into a small sac at the nasal angle of the 
eye, from which the tears are carried into the nose 
by a duct called the nasal duct. When formed in too 
great quantity to be carried off by the natural channels, 
tears flow out over the lids and run down the cheeks, 
as in weeping. 

447. Muscles of the Eye. — The eye is provided with 
six little muscles placed within the socket, by means of 
which it may be turned in various directions. 

448. How We See. — Sight may justly be regarded as 
the most remarkable of all the senses. By means of it, 
through the aid of light, we are able to recognize ob- 
jects at a distance, and, by the aid of suitable instru- 
ments, even at immense distances. 

449. Light. — Light, like sound, is supposed to be pro- 
duced by vibrations, which, emanating from luminous 
bodies and entering the eye, excite the sensitive retina. 
From the retina the optic nerve transmits the impres- 
sion to the sight-centres in the brain, thus giving us the 
impression of light. 

450. Pictures Made by Lenses. — If we hold a con- 



264 SECOND BOOK IN PHYSIOLOGY. 

vex lens before a window, and at a proper distance from 
a screen of thin oiled paper or ground glass, we may see 
upon the screen a perfect picture of the window, but 
much smaller than the original. Lenses may be so 
arranged as to make the pictures of objects larger or 
smaller, or of the same size as the original. 

By noticing carefully the image made by a lens, it 
will be found that the picture formed by it is inverted, 
or wrong side up. This is because the rays of light 
cross each other in passing through the lens. It will 
also be observed that when a thin lens is used the 
image formed is farther away from the lens than when 
a thick one is used. The thicker the lens in propor- 
tion to its diameter, the nearer to it will be the image 
formed. 

451. Chemical Action of Light. — Every one is fa- 
miliar with the fact that a white garment which has 
become yellow, or a piece of unbleached muslin, may be 
made white by exposure to the sun. Many colored fab- 
rics lose their color or fade when long exposed to the 
sun's rays. When the retina of the eye of an animal is 
exposed to the sun its purple color is bleached out in the 
same way. If, however, it is left in contact with its 
natural background, the choroid, and is placed in the 
dark, it soon recovers its color, so that the experiment 
may be repeated several times. 

452. Eye Pictures. — If we allow the image formed 
by a lens to fall upon a retina which has been taken 
from the eye of an animal, the picture will remain upon 
the retina, being bleached upon it by the action of the 
sun's rays. This is exactly what happens when we see 
an object. The lens of the eye, assisted by the cornea, 
forms upon the retina an image which is bleached out in 



THE EYE, AND BOW WE SEE. 265 

the way described. By means of the optic nerve the im- 
pression made upon the retina is transmitted to the brain. 

453. Accommodation. — If we hold a lens at a proper 
distance in front of a screen, we observe that the images 
of near and distant objects are not equally perfect. In 
order to get good images, we must either change the 
position of the lens, or use a thinner lens for distant ob- 
jects and a thicker one for near objects. The lens of the 
eye is fixed at a definite distance from the retina, the 
screen on which the image is to be formed ; and as it 
cannot be exchanged for a thicker or a thinner lens 
when we look at objects at different distances, nature 
has provided the eye with a delicate means by which 
the lens may be made thicker or thinner, and thus 
adjusted to see objects perfectly at different distances. 
This is the purpose of the circular muscle which surrounds 
the lens. The change in the eye in making this adjust- 
ment is termed accommodation. 

Accommodation is exercised only for near objects, as 
the eye is so constructed that it sees without effort ob- 
jects at a distance. A perfectly natural eye cannot ad- 
just itself to see clearly objects which are nearer than five 
to eight inches. (See Experiments 22, 23, pages 276, 277.) 

45 i. Short - sight. — Let us make an experiment. 
Take a lens which will make a distinct image of distant 
objects on a screen held a few inches behind it. Now 
move the screen a little farther from the lens. The im- 
age is now indistinct, but if we hold an object near the 
front of the lens a clear image of it will be formed upon 
the screen. It is evident, then, that if an eye should 
happen to have its retina farther from the lens than 
it should be, it would not be able to see very distant 
objects clearly, although near objects might be seen as 



266 SECOND BOOK IN PHYSIOLOGY. 

distinctly as by an ordinary eye and nearer to the eye. 
Some eyes are thus constructed, the globe of the eye 
being longer than usual, so that the retina is farther 
from the lens. Such an eye is said to be short-sighted. 

455. Long-sight.— In other cases the eyeball is too 
short, bringing the retina too near the lens, so that near 
objects are not well seen, though distant objects are seen 
clearly. Such an eye is said to be long-sighted. 

456. Old-sight. — At the age of forty -five the lens 
begins to become harder, so that it cannot be so accu- 
rately adjusted to near objects, and the individual finds 
it necessary, in reading, to hold the book or paper far- 
ther away from the eyes. This difficulty should be at 
once remedied by convex glasses, which must be changed 
for stronger ones as the person becomes older. 

An old person who finds himself obliged to pull his 
glasses down upon his nose in order to see near objects 
well needs to obtain a stronger pair of glasses. 

457. Why We See Objects Upright. — Although 
the image formed on the retina is inverted, the brain 
traces the rays of light back to the original, and so rec- 
ognizes the object as erect. 

458. Why We See Single. — Although we have two 
eyes, in each of which an image is formed, we ordi- 
narily see objects single. This is because the eyeballs 
are kept by their muscles in such positions in reference 
to each other that the image is formed on the same por- 
tion of the retina of each eye. Sometimes the muscles 
of the eye do not act properly, so the two eyes are not 
focused alike, and then double vision occurs, (See Ex- 
periment 24, page 277.) 

The advantage of two eyes in enabling us to judge of 
the form of objects, their distance, etc., may be readily 



THE EYE, AM) BOW WK SEE. 267 

seen by attempting to thread a needle with one eye 
closed. 

The lens and cornea of the eye are not so regular as 
perfect lenses, and hence do not form absolutely perfect 
images upon the retina. AVhen this irregularity is very 
great, the images are so distorted that objects are seen 
very indistinctly. This defect is called astigmatism. 
It is a frequent cause of headache. 

459. Use of the Iris. — The iris acts as a curtain to 
protect the eye from too intense light, contracting in a 
strong light and dilating when the light is dim. 

460. Color. — The different colors of objects are clue to 
the fact that white light is compound, being composed, 
according to the most recent authorities, of red, green, 
and violet rays. The retina is supposed to possess three 
distinct nerve elements, corresponding to these three pri- 
mary colors. Rays which excite the green element Ave call 
green ; so with red and violet. Rays which excite two 
kinds of elements produce compound colors, as orange, 
yellow, etc. Those which excite all equally give the im- 
pression of white light. (See Experiment 25, page 277.) 

461. Color-blindness. — A person may be born with 
one or more of the color elements of his retina lacking 
or deficient. Such a person is said to be color-blind. 
The red element is most often lacking, so that the indi- 
vidual cannot tell red from green. 

462. Figures in the Eye. — On looking steadily at 
a clear blue sky for some time, numerous bright spots 
may be seen moving to and fro. These are caused by 
the blood - corpuscles passing along the capillaries of 
the retina. "Long-sighted" persons, who are inclined 
to rub the eyes frequently, are often much troubled 
with dark spots before the eyes. These are particles of 



26S SECOND BOOK IN PHYSIOLOGY. 

pigment, or cells which have been detached by rubbing. 
Frequent rubbing of the e}^e should be avoided. 

463. How to Preserve the Eyesight. — 1. The ef- 
fort to accommodate the eye in looking at near objects 
requires the action of several muscles, which must con- 
tinue to act so long as the sight remains fixed upon near 
objects. When the effort is long sustained, these muscles 
become weary, and may become seriously diseased; hence 
the eyes should have frequent rest. 

2. If the eyes become easily tired, and can be used but 
a short time without a blurring of vision, or aching of 
the eyeballs, it is probable that there is some serious de- 
fect, and a competent eye specialist, but not a travelling 
spectacle vender, should be consulted. 

3. J^ever try to read or do work requiring close appli- 
cation of the eyesight with insufficient light. In read- 
ing, have the light come over the shoulder — the left, if 
convenient — and avoid using the eyes in a glaring light. 

4. Avoid exposing the eyes to a sudden bright light. 
When the eyes are opened after being closed for some 
hours, as on awaking from sleep, some little time elapses 
before they are fully accustomed to the light. On this 
account it is not well to employ the eyes in reading im- 
mediately on waking in the morning. 

5. Reading on the cars is injurious to the eyes, on ac- 
count of the shaking which continually changes the dis- 
tance between the book and the eye, and thus taxes most 
severely the organs of accommodation. Reading when 
lying down is also injurious, and for a similar reason. 

6. The common use of the numerous domestic and 
patented eye-washes is a frequent cause of serious disease 
of the eye. When the eyes are simply irritated by ex- 
cessive work, a cold, exposure to dust, or any similar 



THE EYE, AND BOW WK BEE. 269 

cause of irritation, frequenl bathing with cool, tepid, or 
hot water; or rest, with a thin cloth wet in tepid water 
laid over the eyes, is a good and harmless remedy. If 
the case is not speedily relieved by some simple remedy 
of this sort, consult a competent physician. 

7. If lime or any other alkali has gotten into the eyes, 
bathe them with water at once, and as quickly as possible 
apply a weak solution of vinegar, using about a table- 
spoonful in half a glass of water. If vinegar is not at 
hand, put a little oil into the eye and bathe with water. 

464. Dirt in the Eye — If visible, the foreign body 
may usually be removed by a corner of a folded hand- 
kerchief, or by the end of the finger previously moistened 
with oil. If out of sight, under the lids, a loop of hair 
passed under the lid and withdrawn will generally bring 
it out. A piece of steel or other sharp substance which 
has become imbedded in the eyeball should never be left 
to " work out," but a surgeon should be consulted at once. 

465. Inflammation of the Eyes, if attended by 
pain and intolerance of light, demands the attention of 
a skilful physician at once. All inflammations of the 
eye attended by a mattery discharge are contagious by 
contact, and persons suffering in this way should never 
use the same handkerchief, wash-basin, or towel used by 
others, and should sleep alone. In consequence of neg- 
lect of this rule a dangerous disease of the eye sometimes 
extends to a large number of persons. Sucli a case re- 
quires careful medical attention. 

466. Relation of Sight to other Senses. — By the 
information derived through the other senses the knowl- 
edge which we receive through the eye is rendered 
much more useful than it would otherwise be ; for ex- 
ample, we should have no idea of solidity without the 



270 SECOND BOOK IN PHYSIOLOGY. 

sense of touch. Our ideas of distance would be imper- 
fect if we were obliged to depend upon the eye alone. 

467. Alcohol and Tobacco. — Grave diseases of the 
eye are constantly traced to the use of one or both of 
these poisons. Tobacco -blindness is a very common 
maladjr. The first symptom is color-blindness, which 
is followed by haziness of vision, and finally partial or 
complete loss of sight. Several diseases of the eye are 
due to the use of alcoholic drinks. 

SUMMARY. 

1. The simplest eye is a layer of dark pigment covered by transpar- 
ent skin, the nerves of sight spread out between the two. 

2. In man the eye consists of the eyeball, the optic nerve, the eyelids, 
and the tear-gland and ducts. 

3. The eyeball has three investing coats— sclerotic-cornea, choroid- 
als, retina — which enclose three transparent humors, aqueous humor, 
crystalline lens, vitreous humor. 

4. The eyeball is moved by means of six small muscles. 

5. By means of lenses we may produce pictures of objects. 

6. The retina of the eye has a peculiar coloring-matter, which is 
bleached by exposure to light. 

7. In seeing an object, a picture is bleached upon the retina by the 
action of the rays of light. 

8. The eye accommodates itself to different distances by changing 
the form of the crystalline lens. 

9. A healthy eye can adjust itself so as to see objects clearly be- 
tween a point eight inches from the eye and the limit of distant vision. 

10. " Short-sight," "long-sight," and ' ' old-sight " are defects in ac- 
commodation which require the attention of an oculist. 

11. We see objects single when the eyeballs are focused alike. 

12. The iris regulates the amount of light received in the eye. 

13. The retina has distinct elements corresponding to the three pri- 
mary colors — red green, violet. Color-blindness is due to deficiency 
of the corresponding element. 

14. Avoid overtaxing the eyes. 

15. Tobacco -blindness is a common malady. The use of strong 
liquors also leads to disease of the eyes. 



EXPERIMENTS. 

Experiment 1. — Make a thin paste of starch or flour. Stir 
a teaspoonful of the paste in half a glass of water. When well 
mixed, add a drop of tincture of iodine, which may be obtained 
of any druggist. The solution will immediately change to a 
beautiful deep blue color. This is the chemical test for starch. 
A drop of iodine applied to a slice of bread will produce a dark 
blue spot. 

Experiment 2. — Scrape the cut surface of a potato, and place 
a little of the milky juice thus obtained upon a slip of glass 
under a microscope. Multitudes of starch granules will be seen 
floating about or adhering to the surface of the glass. 

Experiment 3. — Put in a flask or a bottle a half-pint of 
water as hot as the hand will bear without burning. Add a 
table-spoonful of sugar or molasses, and a half-teaspoonful of 
yeast. Shake well. Place where the temperature will remain 
at about blood-heat, or a little less. After two or three hours 
numerous bubbles will be seen in the liquid. If now it is sub- 
mitted to the test described in Experiment 26, it will be found 
that alcohol is present, showing that alcohol is formed by fer- 
mentation. 

Experiment 4. — Place in a small flask, such as is shown in 
the accompanying cut (Fig. 48), two or three ounces of beer, wine, 
cider, or any other alcoholic drink or mixture; " temperance 
bitters " answers the purpose admirably. Close the mouth of 
the flask with a cork perforated by a small glass tube or the 
stem of a clay pipe. Gently heat the flask over a flame, apply- 
ing to the end of the tube from time to time a lighted match. 
When the liquid has reached the right temperature, and the air 



272 



SECOND BOOK IN PHYSIOLOGY. 




Fig. 48— Test for Al- 
cohol. 



has been expelled from the flask, the blue 
flame of burning alcohol will appear at 
the outer end of the tube, showing that 
the liquid in the flask contains alcohol. 
If a flask cannot be readily obtained, 
a bottle may be used instead, heating 
it in a basin of water placed on a stove. 
This experiment also illustrates the dis- 
tillation of alcohol, the alcohol being 
burned as rapidly as it escapes from 
the bottle, instead of being condensed 
in a cool vessel. 

Experiment 5. — Place a piece of lean, 
tender steak in alcohol or any strong 
liquor as whiskey or brandy. In a few 
days it will become almost as tough and hard as sole-leather. 

Experiment 6. — Place in a goblet the white of an egg. Add 
two or three table-spoonfuls of strong alcohol. In a short time 
the clear albumen will become opaque, and soon after it will 
become as hard as though it had been dropped into boiling wa- 
ter. Strong alcohol affects all living tissues in the same way. 

Experiment 7. — A few teaspoonfuls of alcohol were placed 
in a glass containing half a pint of water. Into this diluted 
alcohol a small minnow was dropped. The minnow immedi- 
ately showed signs of distress. In five seconds it turned over 
on its back. In five seconds more it floated to the top of the 
water, and in one minute it ceased to give any sign of life. 

Experiment 8. — Soak some iron-filings or bits of iron in 
vinegar for a few days. Add a spoonful of the vinegar, which 
will have dissolved a little of the iron, to a cup of tea. The 
black color which at once appears is evidence of the presence 
of tannin in the tea, which combines with the iron, forming ink. 
Experiment 9. — Procure a specimen of blood by pricking 
the finger. A very small drop is sufficient. After transferring 
to a slip of glass, which should first be moistened by the breath, 



EXPERIMENTS. 273 

immediately cover with a piece of very thin glass, such as is 
used for the purpose by microscopists, also taking the precau- 
tion to breathe upon the covering glass before applying it. This 
will spread out the blood in so thin a layer that it no longer 
presents the deep red color which it had at first. The blood 
may now be examined with a microscope. The blood corpus- 
cles of the frog are much larger than those of human beings, 
and hence are much more easily seen with a small microscope. 
It is not easy to see white corpuscles in human blood, but in 
the blood of the frog they may be readily distinguished. The 
effects of alcohol upon the blood corpuscles may be shown by 
touching a drop to the edge of the cover glass while under the 
T-ticroscope. 

Experiment 10. — Count the pulse while lying down. Assume 
a sitting position, and count again. Stand erect, and again 
count. Now exercise vigorously for two or three minutes — run- 
ning up and down stairs, or jumping up and down, swinging 
the arms vigorously. Immediately after the exercise, count the 
pulse once more. If the pulse is sixty while lying, it should be 
about sixty-five to sixty-eight when sitting, seventy to seventy-five 
when standing, and perhaps eighty to ninety for a few minutes 
after active exercise. If the pulse rate is increased by change 
of position or by exercise very much above these figures, it is 
an indication that the heart is weak. Persons who use alcohol 
and tobacco show weak hearts when submitted to this test. 

Experiment 11. — An experiment which has often been made, 
and which it is quite unnecessary to repeat, beautifully illus- 
trates this regulation of the local blood supply. Divide the 
nerve which controls the blood-vessels of the ear of a white 
rabbit. Immediately the skin, previously white, becomes red 
and congested. In consequence of constantly receiving an un- 
due amount of blood, it grows faster than the other ear, and 
soon exceeds it in size. This explains the formation of the 
rum-blossom, since alcohol paralyzes the nerves which control 
the small blood-vessels. 



274 SECOND BOOK IN PHYSIOLOGY. 

Experiment 12. — A simple experiment will illustrate the ac- 
tion of the vessels of the skin. Draw the unsharpened end of 
a pencil along the skin of the arm. A white line will be pro- 
duced. In a few seconds this will disappear, and a red line 
will take its place, and will remain for some time. The white 
line is due to contraction of the small blood-vessels, and the 
red line to the relaxation or partial paralysis which follows the 
spasmodic contraction. A similar result follows the application 
of cold upon the surface, as in handling snow. Alcohol relaxes 
the small blood-vessels of the entire body. It is in this way 
that it invites apoplexy of the brain and inflammation of the 
lungs, liver, and other organs. 

Experiment 13. — 1. Obtain a quart fruit- jar or a similar 
vessel. By means of a tube, one end of which is placed in the 
mouth and the other inside the jar and reaching to its bottom, 
breathe into the jar for a minute, taking care to draw none of 
the air from the jar back into the lungs. Keep the mouth of 
the jar covered by the hand or a bit of card-board. Now re- 
move the tube and cover the jar. Attach a piece of candle to 
one end of a wire, and, after lighting the candle, let it down into 
the jar. The flame will be extinguished, showing that a candle 
will not burn in air that has been breathed. 2. The presence 
of carbonic acid gas in the breath may also be shown by the 
following experiment: Take two drinking - glasses. Fill one 
glass half full of pure water. In the other place an equal 
quantity of lime-water. By means of the tube make the breath 
bubble through the pure water for one minute. Now breathe 
through the lime-water in the same way. The milky appear- 
ance produced in the lime-water demonstrates the presence of 
carbonic acid gas in the breath. 

Experiment 14. — Ascertain the number of cubic feet of air 
in a school-room. Count the number of scholars, and calcu- 
late the length of time the air will remain pure without being 
changed. Also calculate how many feet of pure air should be 
furnished each hour to supply the number of persons occupy- 



EXPERIMENTS. 275 

inof the room. If the room is provided with ventilating open- 
ings, examine them, and see if the air is passing in the right 
direction. This may be done by holding a piece of thin paper 
or the moistened finger against each register. Estimate the 
rate at which the air is passing, and by calculation determine 
whether the amount is sufficient for the number of persons in 
the room. The air should travel at the rate of about five feet a 
second. 

Experiment 15. — The following simple method of employ- 
ing artificial respiration should be practised until well under- 
stood. Have a person lie down upon a bench or a raised plat- 
form with the face upward, and the head hanging ov r er one 
end. The operator, standing above the person's head, should 
take hold of both arms below the elbows, and draw them stead- 
ily upward above the head, retaining them in position two or 
three seconds ; then allow them to go back to position, and press 
the elbows firmly against the sides of the chest. Drawing the 
arms upw r ard will cause the air to rush into the lungs, and re- 
turning them to position and pressing against the chest forces 
the air out of the lungs. By repeating this simple operation 
twelve to sixteen times a minute, actual breathing may be very 
perfectly imitated. 

Experiment 16. — Cut two blocks of ice to the same form 
and weight. Cover one with flannel, the other with cotton cloth 
of the same thickness. Expose both to the sun, and after an 
hour or two weigh each piece of ice, and see which has lost 
the more. It will be found that the woollen cloth is much the 
better protector for the ice, and for the same reason it affords 
better protection for the body. 

Experiment 17. — Cover the skin of the arm with a piece of 
rubber cloth, oiled silk, or oiled muslin. After an hour remove 
the covering. Notice that the skin is moist. The moisture is 
due to the accumulation of the insensible perspiration, which 
ought to have escaped into the air. This shows the importance 
of wearing porous clothing. The moisture which accumulates 



276 SECOND BOOK IN PHYSIOLOGY. 

in the clothing while wearing a rubber cloak rapidly evaporates 
upon laying the rubber garment aside, and thus causes a chill 
which frequently results in a severe cold. 

Experiment 18. — Tie a cord tightly around the finger. In a 
few moments the finger becomes swollen and cold. The venous 
blood accumulates in it, and the warm, vitalizing blood is kept 
out. The tighter the cord, the more marked the effect produced. 
Constrictions of any sort about the limbs or other parts of the 
body produce the same result in greater or less degree, and so 
occasion injury. 

Experiment 19. — Place in a weak solution of muriatic acid 
a long slender bone, as a sheep's rib or the leg-bone of a fowl. 
In a week or two it will be found that the bone has lost its 
rigidity, although its form is not changed, and it may be bent 
double, or even tied in a knot, if long enough, without breaking. 
This change is due to the absorption of the salts from the 
bone. If the bone is dried and weighed, it will be found that 
it has lost about two-thirds its weight, provided it has remained 
in the solution a sufficient length of time. 

Experiment 20. — The effect of compression upon the mus- 
cles may be readily observed by fixing a large cord or a strap 
tightly around the middle of the forearm. It will be found im- 
possible to use the fingers with any degree of facility. They 
can scarcely be moved, in fact. The lesson to be drawn from 
this experiment is obvious. 

Experiment 21. — Standing or sitting quietly, count the pulse 
very carefully, noting the number of beats per minute. Now 
slowly sip a glass of cold water. After a few seconds, count 
the pulse again. It will be found that the heart beats more 
slowly. The act of swallowing " inhibits " the action of the 
heart. 

Experiment 22. — Take a pair of compasses. Bring the 
points very near together, and, without looking at them, touch 
both at the same time to the end of the forefinger. If they 
are very close together, both will be felt as one point. On sep- 



EXPERIMENTS. 277 

arating them a little, tliey will be distinguished as two points. 
Test various parts of the body, and notice the distance required 
for the points to be felt as two. 

Experiment 23. — Standing before a window, and holding up 
a pencil about fifteen inches from the eye, fix the sight first 
upon some distant object and then upon the pencil. It will be 
observed that when the pencil is seen distinctly the distant ob- 
ject is not well seen, and when looking sharply at the object in 
the distance, the pencil is indistinct and appears double. This 
proves that the eye cannot be adjusted so as to see both near 
and distant objects equally well at the same time. 

Experiment 24. — Place an open book before the eyes at the 
usual distance for reading. Now move the book towards the 
eyes, and observe the point at which the letters are no longer 
seen distinctly. This is called the " near point " of vision, and 
marks the limit of the accommodating power of the eye. 

Experiment 25.- — Hold a pencil before the eyes. Press 
with the finger upon the outer or inner side of the ball of one 
eye. Two pencils will be seen instead of one. The distance 
between the two objects varies with the pressure made. 

Experiment 26. — Prepare a circular disk of card-board about 
three inches in diameter. Divide the surface of the disk into 
three equal parts by lines drawn from the centre to the circum- 
ference. Paint one section with vermilion red, another with 
emerald green, and the third with violet. Now make the disk 
revolve by attaching it to the handle of a top and spinning it. 
When revolving rapidly the three colors of the disk will coalesce, 
giving a white or grayish color. By covering a section or por- 
tions of sections of the disk all different colors may be pro- 
duced. For example, if the violet is covered with white paper, 
the disk, when revolved, will present a bright yellow color, by 
the combination of the red and green rays. If the green is 
partly covered in addition to the violet, the result will be an 
orange. All the colors of the spectrum may be produced in 
this way. 



278 SECOND BOOK IN PHYSIOLOGY. 

Experiment 27. — An experiment with what are known as 
" after-images " confirms this view of the nature of light, and 
also enables us to select complementary colors. Place a ver- 
milion - red wafer on a white or gray ground ; after looking 
steadily at it in a good light for two or three minutes remove 
the wafer, and in its place will be seen, after a few seconds, a 
bluish-green spot of the same size as the wafer. An orange- 
colored wafer will be followed by a sky-blue spot, green by 
pink, and yellow by violet-blue. The color which follows the 
one looked at is said to be complementary to it, since it is 
produced by such rays as, combined with the color first seen, 
will make white light. 

Experiment 28. — Look at some bright object, such as a win- 
dow or a gas-flame, for a moment. Now close the eyes. The 
object will still be seen, and will remain for some minutes, al- 
though the eyes are closed. If this experiment is made by a 
person who is in a state of chronic nicotine poisoning, he will 
notice that pictures seen in this way remain a much longer 
time than they should. This is due to the paralyzing effect of 
tobacco. The coloring matter by which the picture bleached 
upon the retina is obliterated is not supplied with the natural 
promptness, because the cells which produce it, like those of 
the rest of the body, are suffering from the benumbing influ- 
ence of nicotine. 



QUESTIONS FOR REVIEW 

Chapter I. — Physiology, Anatomy, and Hygiene. — Define physiol- 
ogy. Define anatomy. Of what does hygiene treat? 

Chapter II. — Cells, Tissues, Organs.— Of what are all living things 
composed? How do animals and plants grow? Why are animals and 
plants said to be organized? What is the difference between organic 
and inorganic objects? Name the ultimate elements of which the body 
is composed. How are the tissues filled and repaired? What is the 
effect of alcoholic drinks, tobacco, and other narcotics upon the tissues 
and tissue-builders? Define health. What is disease? 

Chapter III. — Nutrition. — What is one of the results of all vital 
work ? Of what do the rjodily wastes consist? Define excretion. What 
is assimilation ? What i*s meant by the term disassimilation f What sub- 
stances are needed for nutrition? What is needed to preserve the health, 
in addition to food, water, and air? Name some substances which 
most seriously disturb the processes of nutrition. How does alcohol 
disturb nutrition? How do tobacco and opium disturb the nutritive 
processes? Do you know of any animal besides man that uses tobacco? 
(Am. — The tobacco-worm.) 

Chapter IV. — Foods. — What is the use of foods? Define a poison. 
What sort of substances do men and other animals require for food? 
What is the difference between the food required by plants and that 
required by animals? From what source do men and animals really 
derive all their food supply? (Arts. — From plants.) Name the six 
food elements. Are condiments food? Of what use in the body are 
starch, sugar, and fats? What tissues are nourished by albumen? 
What tissues are nourished by the salts? Of what use are indigestible 
elements? 

Chapter V. — Drinks. — What is the only substance that will quench 
thirst? Name some of the uses of water. What kinds of impurities 
are found in water? Which of these are most dangerous of all? From 
what sources are the germs found in water chiefly derived? Is ice 
likely to be impure, and when? What are the qualities of pure water? 
(Ans. — Tasteless, colorless, odorless.) May impurities of the w T ater be 



280 SECOND BOOK IN PHYSIOLOGY. 

detected? How may impure water be purified? Is filtration alone a 
perfectly safe method of purifying water? Should water be used as a 
drink freely, or sparingly? Name some unwholesome drinks. Are 
these drinks proper substitutes for water? 

Chapter VI. — The Organs of Digestion. — Define digestion. Do 
plants digest? Name the principal parts of the digestive apparatus. 
How many sets of teeth does each person have? How many teeth in 
each set? When do the permanent teeth begin to appear, and when is 
the set completed? What is the use of the salivary glands? How is 
the gastric juice produced? How" many digestive principles does it 
contain? Name them. What is the intestinal juice? What digestive 
fluid is produced by the liver? What is the portal circulation? What 
fluid is produced by the pancreas? How many digestive principles are 
contained in the pancreatic juice? 

Chapter VII. — The Digestive Fluids. — How many digestive fluids? 
Name them. How many digestible food elements? Name them. 
What does the saliva digest? What does the gastric juice digest? 
What does the bile digest? What does the pancreatic juice digest? 
Why is the pancreatic juice able to digest so manjr different food ele- 
ments ? What does the in testinal j uice digest ? How T is starch digested ? 
How is albumen digested? How are the fats digested? How is cane- 
sugar digested? How are the salts digested? How is starch changed 
in digestion? Into what is cane-sugar converted by digestion? Into 
what is the albumen changed? What change is produced in the fats 
by digestion? In what does the digestion of the salts consist? 

Chapter VIII. — General View of the Digestive Process. — Name the 
five principal divisions of the digestive apparatus. Name the five food 
elements. Name the five digestible food elements. How many diges- 
tive processes? Name them. What other effect has the saliva upon 
the food besides the digestion of starch? What other action has the 
gastric juice besides the digestion of albumen? What other functions 
has the bile besides the digestion of fats? What are the lacteals, and 
what is their use? What is the portal vein? To what organ does it 
convey the blood? 

Chapter IX. — The Hygiene of Digestion. — To what do the chief 
errors respecting diet relate? What are the principal errors relating to 
the manner of eating? What harm from drinking too freely at meals? 
What is the effect of iced foods or drinks upon digestion? Why is it 
injurious to eat between meals? Should one eat just before retiring at 
night? Why is this practice injurious? Mention errors relating to the 
quantity of food. Name those qualities and substances which render 



QUESTIONS FOR REVIEW. 2S1 

food unwholesome. Why arc pepper and other condiments injurious? 
Why is baking-powder harmful? What does vinegar sometimes con 

tain? Mention good substitutes for vinegar. Why is fried food indi- 
gestible? Why should oue avoid the use of pastry? What evil conse- 
quences arise from the use of food containing an excess of albuminous 
elements? What injury may result from the use of excessive quanti- 
ties of fat? Of sugar? Why is candy injurious? What harm may 
result from the use of unripe fruit? What are the dangers of using 
decayed foods? Give some examples of decayed food. (An*. — 
Cheese, undrawn game, decaying fish and meat.) Mention practices 
which are injurious to the teeth. How should the teeth be cared for 
to keep them in health? 

Chapter X. — Alcoholic Drinks, Tobacco, and other Narcotics. — Are 
all narcotics poisonous? Mention the narcotics in most common use. 
(Ans. — Alcohol, tobacco, opium, tea, and coffee.) How is alcohol pro- 
duced? What is the cause of fermentation? How is pure alcohol ob- 
tained? How much alcohol do the various alcoholic drinks contain? 
Is hard cider intoxicating? How long does cider remain sweet after 
being made? Name some other members of the alcohol family besides 
alcohol. Describe the chemical properties of alcohol. Is alcohol a 
poison to plants? Give proofs. Is alcohol a poison to animals? Give 
proofs. Is alcohol a poison to human beings? Give proofs. Describe 
the influence of alcohol upon the stomach. Describe Dr. Beaumont's 
experiments upon Alexis St. Martin. What is the influence of alcohol 
upon digestion? What did Dr. Roberts discover in relation to alcohol? 
What were the effects of four ounces of claret upon digestion? Of 
two ounces of brandy? What dreadful disease of the stomach is some- 
times produced by alcohol? What organ next to the stomach is most 
exposed to injury from alcohol? What name is given to a liver dam- 
aged by alcohol? Is alcohol a food? What evidence have we that it 
is not a food? Does alcohol increase strength? Why does a person 
who has taken alcohol seem to be stronger? What other drugs besides 
alcohol possess the power to lessen tissue waste? Should arsenic or 
opium be considered a food on this account? What did Dr. Parkes 
show respecting the influence of alcohol upon in uscular strength ? What 
has been shown by Drs. Davis and Richardson respecting the effects 
of alcohol upon animal heat? What is the alcohol appetite? What is 
the effect of moderate drinking? What do life-insurance records show? 
What about bitters? Should alcohol be used in cookery? Do candies 
ever contain alcohol? What is absinthe? What was the origin of 
tobacco-using? What is the effect of tobacco upon the stomach? 



282 SECOND BOOK IN PHYSIOLOGY. 

Upon the throat? Upon the ear? What dreadful disease of the lips, 
tongue, or throat, is produced by tobacco? How do we know this 
disease is the result of tobacco-using? What narcotic poison is found 
in tea and coffee? What other injurious substances are contained in 
tea and coffee? What is the effect of tea and coffee drinking upon 
digestion? Are tea and coffee foods? Mention other narcotics which 
are habitually used. What is the poison-habit? 

Chapter XI. — The Blood.— Why is the circulation of the blood 
essential to nutrition? Of what is the blood composed? What is the 
use of red corpuscles? Of white corpuscles? To what may the blood 
be compared? What remarkable property is possessed by the serum 
of the blood? How may the ability of the serum of the blood to 
destroy germs be lost? 

Chapter XII. — The Heart, Blood- Vessels, and Lymphatics. — What 
are the chief means by which the blood is circulated? Describe the 
heart. Which of the cavities of the heart receive blood? Which send 
out blood? By what is the blood conveyed from the heart? What is 
the use of the veins? What are the capillaries? Describe the struct- 
ure of the arteries; of the veins; of the capillaries. What structures 
are found in the veins which are not found in the arteries? Name the 
three circulatory systems. Where does the systemic circulation. begin 
and end? Where does the pulmonary circulation begin and end? 
Through what part of the body does it circulate the blood, and for 
what purpose? From what organs does the portal vein gather blood? 
To what organ does it convey the blood, and for what purpose? Of 
what does the lymphatic system consist? What is the use of the lymph- 
vessels ? Where do the lymph-vessels originate ? Of what is the lymph 
composed ? How does the lymph act as a medium of exchange between 
the blood and tissues? What name is given to the lymph- vessels con- 
nected with the intestines? To the lymph-glands similarly connected? 
What is the use of the lymph-glands? 

Chapter XIII. — How the Blood is Circulated. — Of what does the 
circulatory system consist? What is its centre? To what may the 
heart be compared? How much work is done by the heart in twenty- 
four hours? How is the action of the heart regulated? What is the 
pulse? Where can the pulse be felt? Describe the capillary circula- 
tion. Describe the circulation in the arteries; in the veins. What is 
the difference between venous blood and arterial blood? How is the 
blood supply of an organ regulated? Does the heart ever rest? 

Chapter XIV. — Hygiene of the Heart, Blood, and Blood- Vessels. — 
How may the strength of the heart be increased? What is the effect 



QUESTIONS FOR REVIEW. 283 

of violent exercise upon the heart? What is the effect of heal and cold 
upon the heart? What is the effect of loss of sleep upon the blood? 
What is the effect of anger and other violent exercises upon the heart? 
What is the influence of poor food, condiments, etc., upon the blood? 
Describe the effect of alcohol upon ihe blood. How does alcohol cause 
fatty degeneration? What is the effect of alcohol upon the heart and 
blood-vessels? How does alcohol lessen animal heat? Describe Dr. 
Parkes's experiment in relation to the effect of alcohol upon the pulse. 
What effect does tobacco have upon the heart? What is the effect of 
tobacco upon the pulse? What effect do tea and coffee sometimes have 
upon the heart? What should be done for a person who has fainted? 
What should one do who has taken a severe cold? 

Chapter XV. — The Organs of Respiration. — Name the principal 
parts of the respiratory apparatus. Name the different portions of 
the air-passages. Describe the lungs. About how many air-cells are 
contained in the lungs? What is the pleura? Describe the thorax. 
What is the diaphragm? 

Chapter XVI. — How We Breathe. — What are the two acts of 
breathing called? To what may the chest be compared in its action? 
What causes the air to enter the chest in breathing? Where should 
the principal movement be in the act of breathing? How many breaths 
are taken per minute? Mention and describe the principal modifica- 
tions of breathing. What is the capacity of the lungs? How much 
air is taken in at each breath in ordinary respiration? What is the 
composition of the air? Describe the properties of oxygen. Of what 
use is nitrogen? What are the properties of carbonic-acid gas? How 
may the presence of carbonic-acid gas be detected? How much oxy- 
gen is contained in each ordinary breath when taken in? How much 
of this is absorbed in the lungs? How much carbonic-acid gas is con- 
tained in each expired breath? What else does the breath derive from 
the blood while in the lungs besides carbonic-acid gas? What is the 
most poisonous substance found in the expired breath? What changes 
occur in the blood during respiration? What becomes of the oxygen 
earned to the tissues by the blood? Of what use is oxygen to the tis- 
sues? What is the relation of oxygen to animal heat? To what may 
the body be compared in relation to the production of heat? How 
much heat is given off by the body each twenty-four hours? In what 
part of the body is the production of heat most active? What tissue 
element is consumed in heat production? By what means may the 
accumulation of fat be regulated? Name the different processes con- 
nected with respiration. 



284 SECOND BOOK IN PHYSIOLOGY. 

Chapter XYII. — Hygiene of the Lungs, and Ventilation. — What 
substance is more than all others most essential to life? What is im- 
pure air? Name some of the most common impurities found in the air. 
Mention some of the sources of air impurities. What are germs? 
What is sewer gas? May we be exposed to danger from it? How 
does coal gas destroy life, and how may we be endangered by it? Of 
what is dust largely composed? How may we protect ourselves from 
the dangers of dust? What is disinfection? Name some of the most 
valuable natural disinfectants. Name the most valuable chemical dis- 
infectants. How should sulphur be used in disinfecting a room? How 
much is required? Is the inhalation of sulphur fumes dangerous to 
life? For what purposes, and how, should chloride of lime be used as 
a disinfectant? What symptoms are produced by breath-poisoned air? 
What is the purpose of ventilation? How much air is spoiled each 
hour by a single person? How much pure air should be introduced 
for ventilation per hour for each person? How many openings are 
needed for ventilation? How large an opening is required for each 
person, the opening being covered by a register? Where should the 
fresh -air inlets be placed? How large should the foul-air outlet be for 
each person, and where should it be placed? Should the fresh air be 
admitted warm or cold? If fresh air is admitted cold, where should 
the outlet be placed? With what should foul-air outlets be connected 
to secure good ventilation ? When should the ventilating shaft be 
heated ? How large should the ventilating shaft be ? Why should 
moisture be added to the air in the winter-time ? Describe natural 
breathing. Do civilized men and women breathe alike? Why not? 
Do men and women of savage tribes breathe alike? Why? Under 
what circumstances do civilized men and women breathe alike ? 
Describe some exercises which are good lung gymnastics. What daily 
practice is a good means of preventing colds? What injury results 
from mouth breathing? Describe artificial respiration. What precau- 
tion may be taken to avoid injury from hot gases? What should be 
done in case of choking ? Describe the effect of alcohol upon the 
lungs. What is the effect of tobacco upon the respiratory organs? 

Chapter XVIIL— The Voice and Speech. — Describe the larynx; 
the vocal cords. How is the voice produced? What is speech? By 
what means may the voice be preserved? What kinds of food injure 
the voice? How do alcohol and tobacco affect the voice? 

Chapter XIX. — The Skin and Kidneys. — What are the principal 
parts of the skin? Describe the cuticle ; the dermis. What kinds of 
glands does the skin contain? Describe tliem and their use. What is 



QUESTIONS FOR REVIEW 288 

the amount of perspiration daily produced? What are the uses of per- 
spiration? Describe the hair. What is its use? Describe the nails 
and their use. Name the several uses of the skin. J low soon will 
death occur if the skin is entirely obstructed, and why? Where are 
the kidneys located, and what is their size? Describe the structure of 
the kidney. What are the ureters? What is the purpose of the uri- 
nary secretion? 

Chapter XX. — The Hygiene of the Skin and the Kidneys. — What 
are essential to the health of the skin? Are cosmetics injurious, and 
why? How may the complexion and the general health of the skin 
be best preserved? What dangers connected with the use of hair 
dyes? How may the scalp be kept in a state of health? How should 
the nails be cared for? What is the cause of ingrowing nail? What 
are corns and callus? How should an ordinary burn be treated? A 
severe one? What are the effects of alcohol and tobacco upon the 
skin? What is the effect of tea upon the skin? Name some of the 
principal causes of disease of the kidneys. How does alcohol injure 
the kidneys? What is the influence of tobacco upon the kidneys? 
What other drugs are likely to injure the kidneys? 

Chapter XXI. — Bathing. — Why is frequent bathing necessary? 
What is the effect of water upon the skin? What is the effect of a 
cold bath upon the skin ? A hot bath? What is the proper temperature 
of an ordinary bath? How often should a bath be taken? Describe a 
convenient method of taking a bath. Why is soap needed ? Mention 
the most important rules relating to a bath. 

Chapter XXII. — Clothing. — Name the most important materials 
for clothing in the order of their value. Why is wool preferable. to 
linen? What objection to rubber or mackintosh garments? Why 
must clothing be adapted to the season and weather? How should 
the feet be clothed? How should the neck be clothed? Name some 
of the evils which result from tight lacing. How does tight lacing 
produce gall-stones? How often should the clothing be changed, and 
why? What clothing should be worn at night? How should a bed 
be cared for? What colors sometimes render clothing poisonous? 
How may injury from this source be obviated? 

Chapter XXIII. — The Bones, Their Uses, and How to Care for 
Them. — Of what is the skeleton composed? What is the use of the 
skeleton ? What is the strength of bony tissue as compared with 
oak? Name some of the different forms of bones in the skeleton. 
How does cartilage differ from bone? What is a joint? Describe the 
different structures which enter into a joint. Mention some of the 



286 SECOND BOOK IN PHYSIOLOGY. 

different kinds of joints. How many bones in the skeleton? How 
many of these are found in the head? In the trunk? In the upper ex- 
tremities? In the lower extremities? Name the bones of the trunk. 
What structure is formed by the vertebrae? Name the bones of the 
arm. Name the bones of the leg. Describe the composition of bones. 
What is the difference between the bones of infancy and those of old 
age? Name the several uses of the bones. 

Chapter XXIV. — Hygiene of the Bones. — What do the bones re- 
quire for their proper development ? Name a bone disease which is 
due to a lack of proper food. What is the influence of exercise upon the 
bones? What is the influence, upon the bones, of exercise at too early 
an age? What is the result of sitting in improper positions? Mention 
some common injury to the bones and joints. What should be done 
when a bone is broken or dislocated? What is a sprain? A bunion? 
What influence have alcohol and tobacco upon the bones? What 
is the effect of alcohol upon the blood-making cells found in the 
bones? 

Chapter XXV. — Anatomy and Physiology of the Muscles. — Of 
what is a muscle chiefly composed? How many muscles are found in 
the body? Describe a tendon. Mention some of the different forms 
of muscles. Name and describe the two general classes of muscles. 
How does the heart differ from any other muscle in the body ? Name 
the two most important uses of the muscles of the face. What are 
the principal uses of the muscles of the trunk? What is the most im- 
portant muscle of respiration ? Name the largest muscles of the arm. 
Name the principal movements of the arm. Name the largest muscle 
of Jhe leg; the longest. How does a muscle contract? How does the 
action of the involuntary muscles differ from that of the voluntary 
muscles? How much work is daily done by the muscles of an ordi- 
nary laboren? How much more work is a horse able to do than a 
man? In what way do the muscles employ the bones in movements? 
To what is the chief value of the hand due? Describe the difference 
between the acts of running, walking, and leaping. Name some of the 
general uses of the muscles. How does the use of the muscles regu- 
late nutrition? Of what special sense are the muscles the seat? 

Chapter XXVI. — How to Keep the Muscles Healthy. — What is 
most essential to the health of the muscles? What is the effect of 
neglect to exercise the muscles? What is the effect of exercise upon 
the lungs? Upon the heart? Upon the circulation and all the tissues? 
Why should exercise be regular? What is the special value of gym- 
nastic exercises? Does proper physical exercise tend to morality? 



QUESTIONS FOR REVIEW. 287 

How may games become injurious? What is the effect of improper 
positions? What is the proper position in sitting? In standing? What 
is the effect of alcohol upon the muscles? What produces the chap- 
fallen countenance of a drunkard? What is the effect of alcohol upon 
the strength? Describe Dr. Parkes's experiment. How much was a 
young man's strength diminished by two ounces of brandy? What is 
the intluenoeof tobacco upon development? How has this fact been 
recognized by the French and other governments? What is the in- 
fluence of tea and coffee upon the strength ? 

Chapter XXVII. — The Brain and Nerves. — Why are the brains 
and nerves required? What are two elements of nerve tissue? What 
is a ganglion or nerve centre? Of what is a nerve trunk composed? 
What is the weight of the brain ? What is the average weight of the 
brain in men? Describe the cerebrum. Describe the cerebellum. 
How many nerve cells is the brain supposed to contain ? Describe the 
central ganglia. What and where is the optic thalamus? Describe 
the medulla oblongata. Describe the structure of the spinal cord. 
How 7 many nerves are sent out from the skull? How many from the 
spinal cord? What constitutes the cerebro-spinal nervous system? 
Describe the sympathetic nervous system. In what portions of the 
body are the sympathetic nerves chiefly distributed ? 

Chapter XXVIIL— How We Feel and Think.— What is the differ- 
ence between a nerve centre and a nerve? In what direction in re- 
lation to the brain do sensory nerve fibres convey impulses? In 
what direction do the motor fibres convey impulses? Mention some 
of the different kinds of sensory nerves, special and general. Mention 
the different kinds of motor nerves. What is the essential nature of 
the brain? How do nerves conduct? How long does it take to feel? 
What is reflex action ? What is automatic action ? Mention the most 
important uses of the spinal cord. What is the function of the me- 
dulla oblongata? Of the cerebellum? Of the cerebrum? Describe the 
effect of removal of the cerebrum in different animals. What por- 
tion of the brain is especially essential to enable one to learn a trade? 
What is inhibition, and of what use is this function? How is a habit 
formed? How do we remember? 

Chapter XXIX. — Hygiene of the Brain and the Nerves. —Why is 
mental exercise necessary? Why is too much study harmful? Can 
the brain retain an indefinite amount? How t many distinct facts can 
be remembered by the strongest brain? Why is it injurious to study 
when very weary? How may one remember well? What is the in- 
fluence of mental worry? Of excitement? Why is sleep essential? 



288 SECOND BOOK IN PHYSIOLOGY. 

Why should we cultivate self-control? How may unwholesome food 
affect the brain? What is the effect of overeating? Why is muscular 
exercise essential for students ? How much exercise should a student 
take daily? 

Chapter XXX. — Effects of Alcohol upon the Brain and Nerves. 
— How does alcohol affect the brain ? What is the significance of the 
wiiiske} T flush? What is the condition of a person who is dead drunk? 
How does alcohol escape from the body? What is alcoholic nervous- 
ness? How does alcohol produce sleeplessness? What is delirium 
tremens? What is the effect of alcohol upon nerve centres and fibres? 
What is locomotor ataxia? Is alcohol a stimulant? What are the 
effects of alcohol upon character? What are the hereditary effects of 
alcohol ? Why is moderate drinking dangerous? What are the effects 
of tobacco upon the mind? What is the effect of cigarettes? Are the 
effects of tobacco-using hereditary? What is the effect of opium upon 
the brain and nerves? Of chloral? Of tea and coffee? What is a 
poison-habit? How are poison-habits formed? 

Chapter XXXI.— Special Senses : the Sense of Touch. — What is 
sensation ? How many kinds of sensations ? Mention sensations which 
relate to conditions within the body. Name those which relate to ex- 
ternal objects. What are the latter called? How is pain produced? 
What is the use of pain? Where is the sense of touch located? In 
what parts of the body is it most acute? What is the sense of space, 
or locality? The sense of pressure? The sense of touch? The sense of 
temperature? Of what use is the sense of temperature? What is the 
muscular sense? Where is it located, and what is its use? What are 
the effects of alcohol upon the sense of touch and its modifications? 

Chapter XXXII. — The Sense of Smell. — Where is the olfactory 
sense located ? Of what use is the sense of smell ? How may the sense 
of smell be abused? Why are strong odors objectionable? What are 
the effects of alcohol and tobacco upon the sense of smell ? 

Chapter XXXIII. — The Sense of Taste. — Where is the sense of 
taste located? How many nerves of taste? Is it necessary that a 
substance should possess flavor ? Do we usually recognize flavors by 
the sense of taste alone ? What impressions are recognized by the tip 
of the tongue? By what nerves is the sensation produced by such 
substances as mustard, pepper, etc., recognized? How are sweet and 
bitter substances recognized ? What are the uses of the sense of taste ? 
What is the effect of condiments upon the sense of taste? What is 
the influence of alcohol and tobacco upon this sense? Is alcohol use- 
ful to the mouth as a cleansing agent? 



QUESTIONS FOR REVIEW. 289 

CHAPTER XXXIV. — The Sense of Hearing.— Of what does the sim- 
plest ear consist ? Describe the ear of a barnacle; of a lobster; of a fish; 
of a snake ; of a turtle. In what respects does the external ear of a man 
differ from the ear of a turtle? Describe the internal ear in man. In 
what respect does it differ from a snake's or a turtle's? In what respect 
does the middle ear differ? How do we hear? Describe an experi- 
ment which illustrates the means by which sounds are recognized by 
the ear. By what number of vibrations is the lowest musical note 
produced? The highest? What is the object of the Eustachian tube? 
What is the purpose of the ear-wax? Give some rules for the proper 
care of the ears. What is the influence of tobacco upon the ears? 

Chapter XXXV.— The Eye, and How We See.— Of what does the 
simplest eye consist? Describe the eye of a starfish; of a leech. 
Name the principal parts of the human eye. Describe the sclerotic; 
the cornea; the choroid; the iris; the retina; the vitreous humor; the 
crystalline lens; the aqueous humor; the eye-socket; the eyelids; the 
tear-glands; the ducts; the muscles of the eye. In what respect does 
light resemble sound? How are impressions transmitted from the eye 
to the brain ? Describe an experiment with lenses which illustrates 
the action of the eye. Describe the chemical action of light. What 
has this action to do with seeing? How does the eye adjust itself so 
as to see objects at different distances? What is short sight? Long 
sight? Old sight? Why do we see objects upright? Why do we see 
objects single? How is double vision produced? What is astigma- 
tism? What is the use of the iris? What are the primary colors? 
How are we enabled to see different colors? Explain color blindness. 
What is the cause of figures in the eye? Give some rules for the pres- 
ervation of the eyesight. What should be done if a caustic alkali 
has entered the eye? How may dirt be removed from the eye? 
What should be done in a case of inflammation of the eyes? How is 
sight assisted by the other senses? What is the effect of alcohol and 
tobacco upon the eyes? 
13 



GLOSSARY. 



The following list of words is here presented chiefly 
for the purpose of indicating the pronunciation. Defini- 
tions are given only for words which are not fully ex- 
plained in the text when first used : — 



The lower cavity of the 



Fat. 
Resembling 



Preventive of decav 



Ab do'men. 

trunk. 
Ad'i pose tis sue 
Al bu'mi nous. 

men. 
A mce'ba. 
Am y lop'sin. 
An a tom'i cal 
An ti sep'tic. 

or fermentation. 
A or'ta. 
A'que ous. 
Ar sen'i cal. 
Ar te'ri al. 
A stig'ma tism. 
Au'ri cle. 

Au to mat'ic. Self-acting. 
Ax il'la. Arm-pit. 

Bron'chi al. 
Bun'ion. 

Cap'il la ry. 
Ca'se in. 
Cer e bel'lum. 
Cer'e brum. 
Chlo'ral. 
Cho'roid. 
Clav'i cle. 
Co'ca ine. 
Ooc'cyx. 
Con vo lu'tions. 
Cor'ne a. 
Cor'pus cle. 



albu- 



Crys'tal line. 
Cur'pus stri a'tum. 
Cu'ti cle. 

Deg lu tf tion. 

De lir'i um tre'mens. 

Di'a phragm. 

Dis as sim i la'tion. 

Ep i der'mis. 
Ep i glot'tis. 
Ep'i lep sy. 
Ep i the'li um. 
Eu sta'chi an. 

Ex ere' tion. A substance thrown off 
from the body. 

Fib'u la. 

Gan'gli on. 
Glu'cose. 
Gly'co gen. 
Gym nas' tics. 



Hash'ish. 
He pat'ic. 
Hu'me rus. 
Hy'oid. 

In'cus. 
In hi bi'tion. 
In som'ni a. 
In tes'ti nal. 
I'ris. 



Pertaining to the liver. 



Sleeplessness. 









GLOSSARY. 2! 


Lab'y rinth. 










l!i di us, 


Lac'te al. 










Rec'tus. 


Lar'ynx. 










Ret'i na. 


Lo co motor a tax'i I 


i. A disease 


in 




which the patient 


wa 


Iks 


with 


a 


Sa'crum. 


staggering gait 










Sal'i va ry. 
Sar to' t i us. 


Mal'ie us. 










Scap'u la. 


Mas ti ea'tion. 










Scle rot'ic. 


Me dul'la ob Ion gat; 


. 








Se ba'ceous. 


Mes en ter'ic. 










Se cre'tion. A substance form 


Mi'tral. 










from the blood by a gland. 


Mus'cu lar. 










Sen'so ry. Pertaining to sensation 
Skel'e ton. 


Xar cot'ic. A stupefying 


dn 


g- 




Som nain'bu lism. Sleep walking. 


Nie'o tine. 










Sphyg'mo graph. 


Xi'tro gen. 










Sta'pes. 
Ste ap'sin. 


CE soph'a gus. 










Ster'num. 


01 fac'to ry. 










Su pi na'tion. 


Op'tic thal'a raus. 










Syn on'y mous. Of like meaning. 


Os'se ous. 










Ten'do A chil'lis. 


Pan ere as. 










The o bro'mine. 


Pa pil'Iafc 










Tho rac'ic. Pertaining to the th 


Pa tel'la. 










rax. 


Pec'to ral. 










Tho'rax. 


Per i car Mi urn. 










Tib'i a. 


Per i os'te urn. 










Tra'che a. 


Per i stal'tic. 










Tri'ceps. 


Per spi'ra to ry. 










Tri chi'na. 


Phar yn ge'al. 










Tri cus'pid. 


Phar'ynx. 










Tryp'sin. 


Phos phor es'cence. 


A h 


ght 


simi 


ar 


Tyr o tox'i con. 


to that emitted by 


phc 


sphorus 


as 




seen in the dark. 










Ul'na. 


Plas'ma. 












Pleu'ra. 










Vena ca'va. 


Pneu'mo graph. 










Ven'tri cle. 


Pro na'tion. 










Ver'te bin. 


Pty'a lin. 










Yes'ti bale. 


Pnl'mo na ry. 










Vit 're ous. 


Py lo'rus. 













